FindGTK2: Set INTERFACE_COMPILE_DEFINITIONS target property only if not empty
FindGTK2: Add config directories only if different from include ones
FindGTK2: Do not link libfreetype

As discussed on the mailing list, freetype includes used in GTK2
headers libraries do not require to link the library explicitly (even
though it is already linked by GTK2 libraries.

Also remove _GTK2_ADD_TARGET_LIBRARIES no longer used and use
${FREETYPE_INCLUDE_DIR_ft2build} ${FREETYPE_INCLUDE_DIR_freetype2}
variables instead of ${FREETYPE_INCLUDE_DIRS}
FindGTK2: Add test for components using variables

Use GTK2_LIBRARIES and GTK2_INCLUDE_DIRS variables
FindGTK2: Rename directory for unit tests
Merge topic 'FindGTK2-quiet' into FindGTK2-targets

Conflicts:
	Modules/FindGTK2.cmake
Merge topic 'FindGTK2-targets' into next

f97c7a0 Merge topic 'FindGTK2-quiet' into FindGTK2-targets
286dc0a FindGTK2: Rename directory for unit tests
cecc70a FindGTK2: Add test for components using variables
f9249f6 FindGTK2: Do not link libfreetype
e71ebb6 FindGTK2: Add config directories only if different from include ones
a8b190b FindGTK2: Set INTERFACE_COMPILE_DEFINITIONS target property only if not empty