[CMake] What does `cross-platform' mean?

[Bill Hoffman]

Jed Brown wrote:

> 
> Thanks Bill.  I'm very encouraged by the response this thread has
> generated and optimistic that the Find* modules will become more robust
> without undue effort by module writers.
> 
Well, it is not going to happen over night, but I think we are closer to 
a plan.  I am going to update the wiki with the main three ideas of this 
thread so it does not get lost.

- Standard FOO_DIR for find modules, but environment and cache. 
Environment works like CC and CXX do.

- Add ability to parse compile lines like the ones produced from 
pkg-config and turn them into full paths to libraries.

- Add an easy way to create dependent cache variables, that when changed 
unset a number of other variables.

-Bill