[CMake] cmake on the BGP

[Brad King]

John R. Cary wrote:
> BTW - should a 'CXX.cmake' file include *_C_FLAGS?

In principle no, but it works around some historical cruft
that hasn't been cleaned up yet.

> Curious about how these work.  I assume that cmake does
> a mapping from the OS and compiler to a Platform file, but
> then there are also Compiler files.   Could one put
> the above into Modules/Compiler/XL-CXX.cmake and have
> it work for all platforms?

The Compiler/* directory was just added a couple weeks ago.
Not everything has been converted over to it.

Any flags for a compiler that are independent of the platform
should go in it.

-Brad