[CMake] telling find_package exactly where to find a package

[Tyler Roscoe]

I'll spend some more time reading FindQt4.cmake at work tomorrow, but I
wanted to post this while I'm thinking about it.

I would like to tell find_package where my third-party libraries are (Qt
specifically). Since I know where the libraries are, I could manually
add paths to INCLUDE_DIRS and LINK_LIBRARIES, but FindQt4 already knows
how to do all of that so why duplicate the effort?

This is for an internal build system, so I want to use a specific
version of Qt installed on a networked filesystem to prevent any
weirdness caused by a developer compiling against some random Qt that
she might have on her dev machine.

This seems like a common situation, so surely there's a CMake way to
handle it? I was hoping the PATHS parameter would do what I want but
it's for specifying the path to the FindXXX modules.

Thanks,
tyler