[MERGE #4716 @jackhorton] Fix local --icu/--custom-icu configuration
[MERGE #4716 @jackhorton] Fix local --icu/--custom-icu configuration

Merge pull request #4716 from jackhorton:fix-local-icu

Unblocks Node-ChakraCore#chakracore-master

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