Migrate fontconfig config test to unix scope

Fontconfig has no X11 dependency and is of broader use to us than the X11
context. The test should also disambiguate whether fontconfig support is
successfully detected or not.

This change also removes a false X11 dependency from the freetype test.

Change-Id: I68a596aa06f614a64163772fe29a09edba119a81
Reviewed-by: Girish Ramakrishnan <girish.1.ramakrishnan@nokia.com>