unify include guard defines, __$FILENAME__

without the underscores these clogged up the namespace for autocompleation which was annoying.

source/blender/python/intern/bpy_app.h

@@ -24,9 +24,9 @@
  *  \ingroup pythonintern
  */
 
-#ifndef BPY_APP_H
-#define BPY_APP_H
+#ifndef __BPY_APP_H__
+#define __BPY_APP_H__
 
 PyObject *BPY_app_struct(void);
 
-#endif // BPY_APP_H
+#endif // __BPY_APP_H__