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/generic/blf_py_api.h

@@ -23,4 +23,4 @@
 
 PyObject *BPyInit_blf(void);
 
-#endif  /* __BLF_PY_API_H__ */
+#endif /* __BLF_PY_API_H__ */