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

Remove:
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: r201494