[CMake] custom configuration types and linking with 3rd-party libs

[Brad King]

Brad King wrote:
> Use an IMPORTED library.  This is supported in CMake 2.6:
> 
>   add_library(xx_lib STATIC IMPORTED)
>   set_target_properties(xx_lib PROPERTIES
>     IMPORTED_CONFIGURATIONS "DEBUG;RELEASE"
>     IMPORTED_LOCATION_GUIDEBUG ${XX_DEBUG}
>     IMPORTED_LOCATION_GUIRELEASE ${XX_RELEASE}

Oops, the above two lines should not have "GUI" in them.

-Brad