ClangFormat: apply to source, most of intern

Apply clang format as proposed in T53211.

For details on usage and instructions for migrating branches
without conflicts, see:

https://wiki.blender.org/wiki/Tools/ClangFormat

source/blender/python/intern/bpy_intern_string.h

@@ -41,4 +41,4 @@ extern PyObject *bpy_intern_str_register;
 extern PyObject *bpy_intern_str_self;
 extern PyObject *bpy_intern_str_unregister;
 
-#endif  /* __BPY_INTERN_STRING_H__ */
+#endif /* __BPY_INTERN_STRING_H__ */