Fix a merge bug in preRAsched for handling physreg aliases.
Fix a merge bug in preRAsched for handling physreg aliases.

I've been sitting on this long enough trying to find a test case. I
think the fix should go in now, but I'll keep working on the test case.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@132701 91177308-0d34-0410-b5e6-96231b3b80d8

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