Enable by default -Werror just for bootstrap-debug.mk and default build.

2017-05-19  Martin Liska  <mliska@suse.cz>

	* configure.ac: Add --enable-werror-always just for
	bootstrap-debug (or none build config) and do not add it
	when we are on a release branch.
	* configure: Regenerated.

From-SVN: r248276