[llvm-pdbutil] Fix build.
[llvm-pdbutil] Fix build.

Some platforms require an explicit specialization of std::hash
for PdbRaw_FeaturesSig.  Also a test involving case sensitivity
needed to be fixed.  For now that particular check just accepts
any path even if they're completely different.  Long term we
should output paths in the correct case to match MSVC.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@307426 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm