[1.8>master] [MERGE #4288 @jackhorton] Fix C4800 in RegexHelper
[1.8>master] [MERGE #4288 @jackhorton] Fix C4800 in RegexHelper

Merge pull request #4288 from jackhorton:fix-build-warning

Microsoft/ChakraCore,Microsoft/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,mrkmarron/ChakraCore,mrkmarron/ChakraCore,mrkmarron/ChakraCore