nativetests: fix static crt build
nativetests: fix static crt build

The ChakraCore solution can be built with static CRT
(`msbuild /p:Runtime=static_library ...`). NativeTests.vcxproj should not
specify its own `RuntimeLibrary` property. Should use imported props.

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