cmake update needed

[Tony Kelman]

> Obviously the patches to the modules won't affect the build of cmake
> itself, but they do affect the building of other packages using cmake.
> These patches were all added over years of testing and usage, and are
> required for a useful cmake package.

Sure. Were the reasons for them ever written down? If I'm going to
maintain the package, I do not want to carry local patches forever.
CMake's test suite is very extensive, if it's missing use cases that
are specific to Cygwin then I'm sure upstream would be willing to add
add more tests to catch them in the future. I'm willing to pursue
upstreaming the patches wherever possible, but need test cases to do
so. I've made this request once or twice before and it was ignored.

-Tony