Driver: Lookup program names using llvm::sys::Program::FindProgramByName 
if our usual methods fail. This isn't necessary for running the tool,
but improves the accuracy of logging output.

Also, have GCC tools lookup gcc program path.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67243 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed