Fix right shift by 64 bits detected on CXX/lex/lex.literal/lex.ext/p4.cpp test case on UBSan bootstrap bot.
Fix right shift by 64 bits detected on CXX/lex/lex.literal/lex.ext/p4.cpp
test case on UBSan bootstrap bot.

This fixes the last failure of "check-clang" in UBSan bootstrap bot.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@217294 91177308-0d34-0410-b5e6-96231b3b80d8

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