CMake: prepare for BLENDER_SORTED_LIBS removal

No functional change, this adds LIB definition and args to cmake files.
Without this it's difficult to migrate away from 'BLENDER_SORTED_LIBS'
since there are many platforms/configurations that could break when
changing linking order.

Manually add and enable WITHOUT_SORTED_LIBS to try building
without sorted libs (currently fails since all variables are empty).
This check will eventually be removed.

See T46725.

source/blender/python/intern/CMakeLists.txt

@@ -117,6 +117,9 @@ set(SRC
 	../BPY_extern_clog.h
 )
 
+set(LIB
+)
+
 # only to check if buildinfo is available
 if(WITH_BUILDINFO)
 	add_definitions(-DBUILD_DATE)
@@ -298,4 +301,4 @@ endif()
 
 add_definitions(${GL_DEFINITIONS})
 
-blender_add_lib(bf_python "${SRC}" "${INC}" "${INC_SYS}")
+blender_add_lib(bf_python "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")