AArch64ISelLowering.cpp: Fix a warning. [-Wunused-variable]
AArch64ISelLowering.cpp: Fix a warning. [-Wunused-variable]

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@258618 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 71c1bf1b4f771f35a27c45c3308820af003bde0c)

apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm