* configure.ac (HAVE_LD_BUILDID): New check for ld --build-id
	support.
	(ENABLE_LD_BUILDID): New configuration option.
	* gcc.c [HAVE_LD_BUILDID and ENABLE_LD_BUILDID]
	(LINK_BUILDID_SPEC): New macro.
	(init_spec): If defined, prepend it between LINK_EH_SPEC and
	link_spec.
	* doc/install.texi: Document --enable-linker-build-id option.
	* configure: Rebuild.
	* config.in: Rebuild.

Co-Authored-By: Roland McGrath <roland@redhat.com>

From-SVN: r147029