[PATCH] These builtin functions set errno. Mark them accordingly.

[Chad Rosier]

CC'ing cfe-commits.

> Hi bob.wilson, chandlerc, grosbach, apazos, rjmccall,
>
> A number of library calls that set errno were not behaving correctly with
> -fmath-errno.  Specifically, they were being lowered to native instruction
> and not setting errno.  The changes are based on grepping through the man
> pages.  Please have a look and let me know if I've missed something.
>
>  Chad
>
> http://reviews.llvm.org/D3806
>
> Files:
>   include/clang/Basic/Builtins.def
>