Add --enable-codesign to gdb's configure

macOS requires that the gdb executable be signed in order to be able
to successfully use ptrace.  This must be done after each link.

This patch adds a new --enable-codesign configure option so that this
step can be automated.

gdb/ChangeLog
2018-06-28  Tom Tromey  <tom@tromey.com>

	* NEWS: Mention --enable-codesign.
	* silent-rules.mk (ECHO_SIGN): New variable.
	* configure.ac: Add --enable-codesign.
	* configure: Rebuild.
	* Makefile.in (CODESIGN, CODESIGN_CERT): New variables.
	(gdb$(EXEEXT)): Optionally invoke codesign.

gdb/configure

@@ -745,6 +745,7 @@ AWK
 REPORT_BUGS_TEXI
 REPORT_BUGS_TO
 PKGVERSION
+CODESIGN_CERT
 HAVE_NATIVE_GCORE_TARGET
 TARGET_OBS
 subdirs
@@ -861,6 +862,7 @@ enable_gdbtk
 with_libunwind_ia64
 with_curses
 enable_profiling
+enable_codesign
 with_pkgversion
 with_bugurl
 with_system_zlib
@@ -1550,6 +1552,7 @@ Optional Features:
   --enable-tui            enable full-screen terminal user interface (TUI)
   --enable-gdbtk          enable gdbtk graphical user interface (GUI)
   --enable-profiling      enable profiling of GDB
+  --enable-codesign=CERT  sign gdb with 'codesign -s CERT'
   --disable-rpath         do not hardcode runtime library paths
   --enable-libmcheck      Try linking with -lmcheck if available
   --enable-werror         treat compile warnings as errors
@@ -7050,6 +7053,14 @@ $as_echo "$ac_cv_cc_supports_pg" >&6; }
   CFLAGS="$OLD_CFLAGS"
 fi
 
+CODESIGN_CERT=
+# Check whether --enable-codesign was given.
+if test "${enable_codesign+set}" = set; then :
+  enableval=$enable_codesign; CODESIGN_CERT=$enableval
+fi
+
+
+
 
 
 # Check whether --with-pkgversion was given.