[MS Demangler] Resolve back-references lazily.
[MS Demangler] Resolve back-references lazily.

We need to both record and resolve back-references lazily due to
not being able to know until a demangling is complete whether or
not a name should go into the back-reference table..  This patch
implements lazy resolution of back-references, but we still have
eager recording of back-references.  This will be fixed in a
subsequent patch.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@338736 91177308-0d34-0410-b5e6-96231b3b80d8

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