Fix cmake auto-installer
Commit 69e6a808 accidentally broke the feature of automatically installing cmake on the fly if it isn't present.
It's easy too fix.
TBH, I never liked this feature. It's counter-intuitive, and doesn't address the notion of dependencies in the proper way. cmake is a significant piece of software to build, and in my opinion it is better to have the users download cmake from their distribution instead of trying to compile it.
Edited by Emmanuel Thomé
