[utils] Support -mtriple=powerpc64
[utils] Support -mtriple=powerpc64

Summary: test/CodeGen/PowerPC/pr33093.ll uses both powerpc64 (big-endian) and powerpc64le while the former was unsupported.

Subscribers: nemanjai

Differential Revision: https://reviews.llvm.org/D39164

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@316297 91177308-0d34-0410-b5e6-96231b3b80d8

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