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/freestyle/intern/python/BPy_StrokeAttribute.h

@@ -37,13 +37,13 @@ extern "C" {
 
 extern PyTypeObject StrokeAttribute_Type;
 
-#define BPy_StrokeAttribute_Check(v) (PyObject_IsInstance((PyObject *)v, (PyObject *)&StrokeAttribute_Type))
+#define BPy_StrokeAttribute_Check(v) \
+  (PyObject_IsInstance((PyObject *)v, (PyObject *)&StrokeAttribute_Type))
 
 /*---------------------------Python BPy_StrokeAttribute structure definition----------*/
 typedef struct {
-	PyObject_HEAD
-	StrokeAttribute *sa;
-	bool borrowed; /* true if *sa is a borrowed reference */
+  PyObject_HEAD StrokeAttribute *sa;
+  bool borrowed; /* true if *sa is a borrowed reference */
 } BPy_StrokeAttribute;
 
 /*---------------------------Python BPy_StrokeAttribute visible prototypes-----------*/