[CMake] make output two two streams: concise to stdout and verbose to a file

[Dave Yost]

When I do an ordinary make, it would be nice if in addition to the the concise output going to the screen, verbose output would go to a file in the root of the build folder.

This way, after the fact I can see exactly what happened with the build I just did. If I have to build again with VERBOSE=1, it’s extra trouble and time, and  and the initial condition likelly is different.

This feature would be especially convenient in an IDE where setting VERBOSE=1 and then unsetting it again is cumbersome.