Blenloader: move ghost include path from INC to TEST_INC

The Ghost dependency was added to avoid a memory leak (rBc7a1e115b507),
but since that's only for the unit tests, it's better to add the path to
`TEST_INC`.

source/blender/blenloader/CMakeLists.txt

@@ -34,7 +34,6 @@ set(INC
   ../sequencer
   ../windowmanager
   ../../../intern/clog
-  ../../../intern/ghost
   ../../../intern/guardedalloc
 
   # for writefile.c: dna_type_offsets.h
@@ -114,6 +113,7 @@ if(WITH_GTESTS)
     tests/blendfile_loading_base_test.h
   )
   set(TEST_INC
+    ../../../intern/ghost
   )
   set(TEST_LIB
     bf_blenloader