[CMake] Invoking CMakle outside of the build/source dir.

[Campbell Barton]

Hi, A handful of times I would have found it useful to run cmake
without having to be in the build dir, mostly there is some way to
change the CWD or write a shell wrapper, nevertheless it could still
be useful when launching builds from scripts or more limited
environments.

Is there some way to do this?:
cmake /some/source/dir /some/build/dir

... rather than
cd /some/source/dir ; cmake /some/build/dir
-- 
- Campbell