Simplify WinCOFFObjectWriter::recordRelocation.
Simplify WinCOFFObjectWriter::recordRelocation.

It looks like that when this code was written recordRelocation could
be called with A-B where A and B are in the same section. The
expression evaluation logic these days makes sure those are folded, so
some of this code was dead.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@306053 91177308-0d34-0410-b5e6-96231b3b80d8

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