Fix gnulib's lstat replacement in C++ namespace mode

Fixes:

 unittests/string_view-selftests.c: In member function 'gnulib::_gl_lstat_wrapper::operator gnulib::_gl_lstat_wrapper::type() const':
 unittests/string_view-selftests.c:11432:22: error: expected primary-expression before ';' token
      return ::rpl_stat;
		       ^

The problem is that the lstat replacement depends on the stat
(function) declaration, which is only declared afterwards.  The fix is
simply to declare lstat after stat.

gdb/defs.h

@@ -34,7 +34,6 @@
 #undef PACKAGE_TARNAME
 
 #include <config.h>
-#include "bfd.h"
 
 #include <sys/types.h>
 #include <limits.h>

gdb/gdb_bfd.c

@@ -66,7 +66,7 @@ struct gdb_bfd_data
       needs_relocations (0),
       crc_computed (0)
   {
-    struct stat buf;
+    sys_stat buf;
 
     if (bfd_stat (abfd, &buf) == 0)
       {
@@ -355,24 +355,61 @@ gdb_bfd_iovec_fileio_close (struct bfd *abfd, void *stream)
   return 0;
 }
 
+/* Convert between a struct stat (potentially a gnulib replacement)
+   and a sys_stat (the system's struct stat).  */
+
+static sys_stat
+to_sys_stat (struct stat *st)
+{
+  sys_stat sst {};
+
+#define COPY(FIELD) \
+  sst.FIELD = st->FIELD
+
+  COPY (st_dev);
+  COPY (st_ino);
+  COPY (st_mode);
+  COPY (st_nlink);
+  COPY (st_uid);
+  COPY (st_gid);
+  COPY (st_rdev);
+
+  /* Check for overflow?  */
+  COPY (st_size);
+
+  // Should probably check _GL_WINDOWS_STAT_TIMESPEC and refer to
+  // st_atim, etc. instead.
+  COPY (st_atime);
+  COPY (st_mtime);
+  COPY (st_ctime);
+
+#undef COPY
+
+  return sst;
+}
+
 /* Wrapper for target_fileio_fstat suitable for passing as the
    STAT_FUNC argument to gdb_bfd_openr_iovec.  */
 
 static int
 gdb_bfd_iovec_fileio_fstat (struct bfd *abfd, void *stream,
-			    struct stat *sb)
+			    sys_stat *sb)
 {
   int fd = *(int *) stream;
   int target_errno;
   int result;
 
-  result = target_fileio_fstat (fd, sb, &target_errno);
+  struct stat st;
+
+  result = target_fileio_fstat (fd, &st, &target_errno);
   if (result == -1)
     {
       errno = fileio_errno_to_host (target_errno);
       bfd_set_error (bfd_error_system_call);
     }
 
+  *sb = to_sys_stat (&st);
+
   return result;
 }
 
@@ -818,7 +855,7 @@ gdb_bfd_openr_iovec (const char *filename, const char *target,
 					void *stream),
 		     int (*stat_func) (struct bfd *abfd,
 				       void *stream,
-				       struct stat *sb))
+				       sys_stat *sb))
 {
   bfd *result = bfd_openr_iovec (filename, target,
 				 open_func, open_closure,

gdb/gdb_bfd.h

@@ -154,7 +154,7 @@ gdb_bfd_ref_ptr gdb_bfd_openr_iovec (const char *filename, const char *target,
 							void *stream),
 				     int (*stat_func) (struct bfd *abfd,
 						       void *stream,
-						       struct stat *sb));
+						       sys_stat *sb));
 
 /* A wrapper for bfd_openr_next_archived_file that initializes the
    gdb-specific reference count.  */

gdb/jit.c

@@ -124,11 +124,11 @@ mem_bfd_iovec_pread (struct bfd *abfd, void *stream, void *buf,
 /* For statting the file, we only support the st_size attribute.  */
 
 static int
-mem_bfd_iovec_stat (struct bfd *abfd, void *stream, struct stat *sb)
+mem_bfd_iovec_stat (struct bfd *abfd, void *stream, sys_stat *sb)
 {
   struct target_buffer *buffer = (struct target_buffer*) stream;
 
-  memset (sb, 0, sizeof (struct stat));
+  memset (sb, 0, sizeof (sys_stat));
   sb->st_size = buffer->size;
   return 0;
 }

gdb/symfile.c

@@ -1260,7 +1260,7 @@ separate_debug_file_exists (const std::string &name, unsigned long crc,
 {
   unsigned long file_crc;
   int file_crc_p;
-  struct stat parent_stat, abfd_stat;
+  sys_stat parent_stat, abfd_stat;
   int verified_as_different;
 
   /* Find a separate debug info file as if symbols would be present in

gdbsupport/common-types.h

@@ -32,8 +32,21 @@ typedef unsigned long long ULONGEST;
 
 #else /* GDBSERVER */
 
+/* Gnulib may replace struct stat with its own version.  Bfd does not
+   use gnulib, so when we call into bfd, we must use the system struct
+   stat.  */
+#define __need_system_sys_stat_h 1
+
+#include <sys/stat.h>
+
 #include "bfd.h"
 
+typedef struct stat sys_stat;
+
+#undef __need_system_sys_stat_h
+
+#include <sys/stat.h>
+
 /* * A byte from the program being debugged.  */
 typedef bfd_byte gdb_byte;
 

gnulib/import/sys_stat.in.h

@@ -536,40 +536,6 @@ _GL_WARN_ON_USE (lchmod, "lchmod is unportable - "
 #endif
 
 
-#if @GNULIB_LSTAT@
-# if ! @HAVE_LSTAT@
-/* mingw does not support symlinks, therefore it does not have lstat.  But
-   without links, stat does just fine.  */
-#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
-#   define lstat stat
-#  endif
-_GL_CXXALIAS_RPL_1 (lstat, stat, int, (const char *name, struct stat *buf));
-# elif @REPLACE_LSTAT@
-#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
-#   undef lstat
-#   define lstat rpl_lstat
-#  endif
-_GL_FUNCDECL_RPL (lstat, int, (const char *name, struct stat *buf)
-                              _GL_ARG_NONNULL ((1, 2)));
-_GL_CXXALIAS_RPL (lstat, int, (const char *name, struct stat *buf));
-# else
-_GL_CXXALIAS_SYS (lstat, int, (const char *name, struct stat *buf));
-# endif
-# if @HAVE_LSTAT@
-_GL_CXXALIASWARN (lstat);
-# endif
-#elif @GNULIB_OVERRIDES_STRUCT_STAT@
-# undef lstat
-# define lstat lstat_used_without_requesting_gnulib_module_lstat
-#elif defined GNULIB_POSIXCHECK
-# undef lstat
-# if HAVE_RAW_DECL_LSTAT
-_GL_WARN_ON_USE (lstat, "lstat is unportable - "
-                 "use gnulib module lstat for portability");
-# endif
-#endif
-
-
 #if @REPLACE_MKDIR@
 # if !(defined __cplusplus && defined GNULIB_NAMESPACE)
 #  undef mkdir
@@ -781,6 +747,38 @@ _GL_WARN_ON_USE (stat, "stat is unportable - "
 # endif
 #endif
 
+#if @GNULIB_LSTAT@
+# if ! @HAVE_LSTAT@
+/* mingw does not support symlinks, therefore it does not have lstat.  But
+   without links, stat does just fine.  */
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define lstat stat
+#  endif
+_GL_CXXALIAS_RPL_1 (lstat, stat, int, (const char *name, struct stat *buf));
+# elif @REPLACE_LSTAT@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef lstat
+#   define lstat rpl_lstat
+#  endif
+_GL_FUNCDECL_RPL (lstat, int, (const char *name, struct stat *buf)
+                              _GL_ARG_NONNULL ((1, 2)));
+_GL_CXXALIAS_RPL (lstat, int, (const char *name, struct stat *buf));
+# else
+_GL_CXXALIAS_SYS (lstat, int, (const char *name, struct stat *buf));
+# endif
+# if @HAVE_LSTAT@
+_GL_CXXALIASWARN (lstat);
+# endif
+#elif @GNULIB_OVERRIDES_STRUCT_STAT@
+# undef lstat
+# define lstat lstat_used_without_requesting_gnulib_module_lstat
+#elif defined GNULIB_POSIXCHECK
+# undef lstat
+# if HAVE_RAW_DECL_LSTAT
+_GL_WARN_ON_USE (lstat, "lstat is unportable - "
+                 "use gnulib module lstat for portability");
+# endif
+#endif
 
 #if @GNULIB_UTIMENSAT@
 /* Use the rpl_ prefix also on Solaris <= 9, because on Solaris 9 our utimensat