[CMake] MinGW detection question

[E. Wing]

I'm playing around with the MinGW generator. I was wondering if there
is a special environmental variable that CMake will check for finding
mingw32-make.exe. MinGW is not in my PATH so everytime I specify the
MinGW generator in CMakeSetup, it complains it can't find the make
program. I was hoping I could make CMake happy without adding more
stuff to my PATH.

Thanks,
Eric