Import the strerror_r-posix module and use it in GDB.

Import the strerror_r-posix module and use it in GDB.

Makes sure to assign the return value of strerror_r to an int,
so that we get a compile error if we accidentally get the
wrong version.

gdb/ChangeLog:

2019-11-15  Christian Biesinger  <cbiesinger@google.com>

	* config.in: Regenerate.
	* configure: Regenerate.
	* gdbsupport/common.m4: No longer check for strerror_r.
	* gdbsupport/posix-strerror.c (safe_strerror): Always call the
	POSIX version of strerror_r, now that gnulib provides it if
	necessary.

gdb/gdbserver/ChangeLog:

2019-11-15  Christian Biesinger  <cbiesinger@google.com>

	* config.in: Regenerate.
	* configure: Regenerate.

gnulib/ChangeLog:

2019-11-15  Christian Biesinger  <cbiesinger@google.com>

	* Makefile.in: Regenerate.
	* aclocal.m4: Regenerate.
	* config.in: Regenerate.
	* configure: Regenerate.
	* import/Makefile.am: Update.
	* import/Makefile.in: Regenerate.
	* import/extra/config.rpath: New file.
	* import/glthread/lock.c: New file.
	* import/glthread/lock.h: New file.
	* import/glthread/threadlib.c: New file.
	* import/m4/gnulib-cache.m4: Update.
	* import/m4/gnulib-comp.m4: Update.
	* import/m4/lib-ld.m4: New file.
	* import/m4/lib-link.m4: New file.
	* import/m4/lib-prefix.m4: New file.
	* import/m4/lock.m4: New file.
	* import/m4/strerror_r.m4: New file.
	* import/m4/threadlib.m4: New file.
	* import/strerror_r.c: New file.
	* update-gnulib.sh: Import strerror_r-posix.

Change-Id: I5cfeb12a5203a4cd94a78581541e6085a68685c3