sed and head portability fixes in ld version check.

libstdc++-v3/:
	PR libstdc++/38923
	* acinclude.m4 (GLIBCXX_CHECK_LINKER_FEATURES): Avoid 'head',
	use sed script portable to Solaris /bin/sed for extracting ld
	version.
	* configure: Regenerate.

libgomp/:
	* acinclude.m4 (LIBGOMP_CHECK_LINKER_FEATURES): Avoid 'head',
	use sed script portable to Solaris /bin/sed for extracting ld
	version.
	* configure: Regenerate.

From-SVN: r152315