gdb/solib: make solib_ops::in_dynsym_resolve_code optional

Two solib ops implementations have dummy implementations for the
in_dynsym_resolve_code callback.  Make it optional, to avoid this.

Change-Id: I786776fb82ce1b96335a97713fbfe8074c84c00c
Reviewed-By: Guinevere Larsen <guinevere@redhat.com>

gdb/solib-aix.c

@@ -489,14 +489,6 @@ solib_aix_current_sos ()
   return sos;
 }
 
-/* Implement the "in_dynsym_resolve_code" solib_ops method.  */
-
-static bool
-solib_aix_in_dynsym_resolve_code (CORE_ADDR pc)
-{
-  return false;
-}
-
 /* Implement the "bfd_open" solib_ops method.  */
 
 static gdb_bfd_ref_ptr
@@ -676,7 +668,7 @@ const solib_ops solib_aix_so_ops =
   solib_aix_solib_create_inferior_hook,
   solib_aix_current_sos,
   nullptr,
-  solib_aix_in_dynsym_resolve_code,
+  nullptr,
   solib_aix_bfd_open,
   nullptr,
   nullptr,

gdb/solib-darwin.c

@@ -353,15 +353,6 @@ darwin_read_exec_load_addr_at_init (struct darwin_info *info)
   return darwin_validate_exec_header (load_addr);
 }
 
-/* Return true if PC lies in the dynamic symbol resolution code of the
-   run time loader.  */
-
-static bool
-darwin_in_dynsym_resolve_code (CORE_ADDR pc)
-{
-  return false;
-}
-
 /* A wrapper for bfd_mach_o_fat_extract that handles reference
    counting properly.  This will either return NULL, or return a new
    reference to a BFD.  */
@@ -640,7 +631,7 @@ const solib_ops darwin_so_ops =
   darwin_solib_create_inferior_hook,
   darwin_current_sos,
   nullptr,
-  darwin_in_dynsym_resolve_code,
+  nullptr,
   darwin_bfd_open,
   nullptr,
   nullptr,

gdb/solib.c

@@ -1325,8 +1325,10 @@ solib_create_inferior_hook (int from_tty)
 bool
 in_solib_dynsym_resolve_code (CORE_ADDR pc)
 {
-  return (gdbarch_so_ops (current_inferior ()->arch ())
-	  ->in_dynsym_resolve_code (pc));
+  const auto in_dynsym_resolve_code
+    = gdbarch_so_ops (current_inferior ()->arch ())->in_dynsym_resolve_code;
+
+  return in_dynsym_resolve_code && in_dynsym_resolve_code (pc);
 }
 
 /* Implements the "sharedlibrary" command.  */