Executable search on MinGW32

Hi,

I have been trying to get clang working with MinGW32, and ran into a
number of minor problems. One of them is the way executables (e.g.
clang-cc, as, ld) are searched, usually with GetProgramPath(). On
Windows, these executables need to have ".exe" appended to be found.

This needed changes in both clang and llvm. Please see the attached
diffs.

clang-findexe.diff (755 Bytes)

llvm-findexe.diff (1.14 KB)