sys::findProgramByName(): [Win32] Tweak to pass lowercase .exe to SearchPath() to appease clang Driver's tests.
sys::findProgramByName(): [Win32] Tweak to pass lowercase .exe to SearchPath() to appease clang Driver's tests.

It seems SearchPath() doesn't show actual extension on the filesystem.

FIXME: Shall we use FindFirstFile() here?

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@221246 91177308-0d34-0410-b5e6-96231b3b80d8

dslab-epfl/asap,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,dslab-epfl/asap,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,dslab-epfl/asap,GPUOpen-Drivers/llvm,dslab-epfl/asap,GPUOpen-Drivers/llvm,dslab-epfl/asap,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,dslab-epfl/asap,GPUOpen-Drivers/llvm,dslab-epfl/asap,GPUOpen-Drivers/llvm