Add support to Cygwin
Add support to Cygwin

This matches any Cygwin version to be mapped as a Linux platform.
The cygwin platform identification normally should match the CYGWIN_NT-X
where X is the underlying Windows version. Tested this on Windows 10 with
Cygwin x86_64 and was able to build fips-hello-world project.

Closes #128

code-disaster/fips,floooh/fips,floooh/fips,code-disaster/fips,floooh/fips