enable/disable for cmake

[Elan Ruusamäe]

for autotools we have macros for --enable, --disable, --with --without
http://git.pld-linux.org/?p=packages/rpm-build-macros.git;a=blob;f=rpm.macros;h=fb44ba49b4492d80ddf696d04c427b16f9661d96;hb=b89253d0468b9a528a89c47bfc36e7274666310f#l339

would be nice to have same for cmake as well
how to name them?

for cmake it's simplier: need only one macro, as there's only need for 
-DFOO=ON|OFF

-- 
glen