[MERGE #3183 @MSLaguana] Fixing environment variable parsing in PAL
[MERGE #3183 @MSLaguana] Fixing environment variable parsing in PAL

Merge pull request #3183 from MSLaguana:users/jithomso/fixEnvironmentParsing

The `compare` function used in `MiscGetenv` checks if the first argument
is a prefix of the second argument, but `MiscGetenv` was passing the longer
argument (e.g. "HOME=/users/foo") first, meaning that it would never
find any environment variable.

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