PKG_CHECK_MODULES: Check if $pkg_cv_[]$1[]_LIBS works

It is quite normal to have headers without library on multilib OSes.
Add AC_TRY_LINK to PKG_CHECK_MODULES to check if $pkg_cv_[]$1[]_LIBS
works.

config/

	PR binutils/26301
	* pkg.m4 (PKG_CHECK_MODULES): Add AC_TRY_LINK to check if
	$pkg_cv_[]$1[]_LIBS works.

binutils/

	PR binutils/26301
	* configure: Regenerated.

gdb/

	PR binutils/26301
	* configure: Regenerated.