import strstr and strerror modules

import strstr and strerror modules

This imports the gnulib strstr and strerror modules.  It doesn't make
any other changes to gdb; I found it simpler to work with the branch
if I made the changes more indepdendent than I had previously.

2013-11-18  Tom Tromey  <tromey@redhat.com>

	* gnulib/update-gnulib.sh (IMPORTED_GNULIB_MODULES): Add strerror
	and strstr.
	* gnulib/aclocal.m4: Update.
	* gnulib/config.in: Update.
	* gnulib/configure: Update.
	* gnulib/import/Makefile.am: Update.
	* gnulib/import/Makefile.in: Update.
	* gnulib/import/errno.in.h: New.
	* gnulib/import/intprops.h: New.
	* gnulib/import/m4/errno_h.m4: New.
	* gnulib/import/m4/gnulib-cache.m4: Update.
	* gnulib/import/m4/gnulib-comp.m4: Update.
	* gnulib/import/m4/strerror.m4: New.
	* gnulib/import/m4/strstr.m4: New.
	* gnulib/import/m4/sys_socket_h.m4: New.
	* gnulib/import/strerror-override.c: New.
	* gnulib/import/strerror-override.h: New.
	* gnulib/import/strerror.c: New.
	* gnulib/import/strstr.c: New.