Freestyle: use bool instead of int.

Patch contribution by flokkievids (Folkert de Vries).  Thanks!

source/blender/freestyle/intern/python/BPy_Interface0D.h

@@ -47,7 +47,7 @@ extern PyTypeObject Interface0D_Type;
 typedef struct {
 	PyObject_HEAD
 	Interface0D *if0D;
-	int borrowed; /* non-zero if *if0D is a borrowed object */
+	bool borrowed; /* true if *if0D is a borrowed object */
 } BPy_Interface0D;
 
 /*---------------------------Python BPy_Interface0D visible prototypes-----------*/