Handle reserved registers more accurately in handleMove().

Handle reserved registers more accurately in handleMove().

Reserved register live ranges look like a set of dead defs - any uses of
reserved registers are ignored.

Instead of skipping the updating of reserved register operands entirely,
just ignore the use operands and treat the def operands normally.

No test case, handleMove() is not commonly used yet.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165060 91177308-0d34-0410-b5e6-96231b3b80d8