re PR target/57792 (toplevel configure should enable "--with-sysroot="`xcrun --show-sdk-path`"" for darwin13 and later)

2013-07-10  Jack Howarth  <howarth@bromo.med.uc.edu>

	PR target/57792
	* configure.ac: Use --with-sysroot=\"`xcrun --show-sdk-path`\" on darwin13 and later.
	* configure: Regenerated.

From-SVN: r200890