Added posix function gettimeofday to LibFunc::Func for all platforms but Windows.

Added posix function gettimeofday to LibFunc::Func for all platforms but Windows.

*NOTE* In a recent version of posix, they added the restrict keyword to the
arguments for this function. From some spelunking it seems that on some
platforms, the call has restrict on its arguments and others it does not. Thus I
left off the restrict keyword from the function prototype in the comment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185501 91177308-0d34-0410-b5e6-96231b3b80d8