[binutils-gdb] Disable all target libraries if not building gcc

[sergiodj+buildbot@redhat.com]

*** TEST RESULTS FOR COMMIT 35fece71d50e1883e67fcd28c69245de4335b8b5 ***

Author: H.J. Lu <hjl.tools@gmail.com>
Branch: master
Commit: 35fece71d50e1883e67fcd28c69245de4335b8b5

Disable all target libraries if not building gcc
Don't build target libraries if not building gcc.

	* configure.ac (target_configdirs): Unset if not building gcc.
	* configure: Regenerated.