Fix build with CMake >= 3.28.0. FREETYPE_LIBRARY has not officially been
part of the user-facing interface of the FindFreetype module since CMake
2.6.0 [1] and has only been coincidentally defined up until this point.

[1] https://gitlab.kitware.com/cmake/cmake/-/commit/d18fb61c76c720ec5b1ac2cc4f30a5beaf071c33

--- gemrb/plugins/TTFImporter/CMakeLists.txt.orig	2022-08-29 19:10:39 UTC
+++ gemrb/plugins/TTFImporter/CMakeLists.txt
@@ -1,8 +1,8 @@
-IF (FREETYPE_LIBRARY)
+IF (FREETYPE_LIBRARIES)
 	INCLUDE_DIRECTORIES( ${FREETYPE_INCLUDE_DIRS})
 	INCLUDE_DIRECTORIES(${Iconv_INCLUDE_DIR})
 
 	ADD_GEMRB_PLUGIN (TTFImporter TTFFontManager.cpp TTFFont.cpp Freetype.cpp)
-	TARGET_LINK_LIBRARIES( TTFImporter ${FREETYPE_LIBRARY} )
+	TARGET_LINK_LIBRARIES(TTFImporter ${FREETYPE_LIBRARIES})
 	TARGET_LINK_LIBRARIES(TTFImporter ${Iconv_LIBRARY} ${CHARSET_LIBRARY})
-ENDIF (FREETYPE_LIBRARY)
+ENDIF (FREETYPE_LIBRARIES)
