[MERGE #4027 @sigatrev] ARM64: unlink src before reusing
[MERGE #4027 @sigatrev] ARM64: unlink src before reusing

Merge pull request #4027 from sigatrev:unlink

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