[Bug middle-end/21743] Enable __builtin_clog

[giovannibajo at libero dot it]

-- 
Bug 21743 depends on bug 21784, which changed state.

Bug 21784 Summary: [3.4/4.0/4.1 Regression] Using vs builtin names
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21784

           What    |Old Value                   |New Value
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21743