Moved function declarations from BKE_DerivedMesh.h to BKE_mesh_runtime.h

The function definitions still reside in DerivedMesh.c. Once we're done
porting all the DerivedMesh use to Mesh, we'll move the still-relevant
functions to mesh_runtime.c. This move is now cumbersome due to shared
statically-declared utility functions in DerivedMesh.c

source/blender/blenkernel/intern/multires.c

@@ -51,6 +51,7 @@
 #include "BKE_cdderivedmesh.h"
 #include "BKE_mesh.h"
 #include "BKE_mesh_mapping.h"
+#include "BKE_mesh_runtime.h"
 #include "BKE_modifier.h"
 #include "BKE_multires.h"
 #include "BKE_paint.h"