Fix gold to use mallinfo2 if available instead of deprecated mallinfo.

gold/
	PR gold/26585
	* configure.ac: Add check for mallinfo2.
	* configure: Regenerate.
	* main.cc (main): Use mallinfo2 if available.

	PR gold/26585
	* main.cc (main): Fix typo in previous patch.

	PR gold/26585
	* config.in: Regenerate from previous commit.

(cherry picked from commit 4ee60495)
(cherry picked from commit cc184971)
(cherry picked from commit 9331846e)