[utils] make retq/retl regex an option that is off by default
[utils] make retq/retl regex an option that is off by default

Ideally, we should compare 32- and 64-bit versions to see if the 
ret line is the only difference and then insert the regex only
in that case. But this is a quick hack to avoid a bunch of noise
as existing tests are updated.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@316443 91177308-0d34-0410-b5e6-96231b3b80d8

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