Cygwin defines log2 as a macro. Undef it here IFF it has already been defined,
so that we always get the inline function instead. Remember, kids, like it says
in the GCC manual, "An Inline Function is As Fast As a Macro."


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11815 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed