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/gpu/gpu_py_element.h

@@ -23,11 +23,10 @@
 
 extern PyTypeObject BPyGPUIndexBuf_Type;
 
-#define BPyGPUIndexBuf_Check(v)        (Py_TYPE(v) == &BPyGPUIndexBuf_Type)
+#define BPyGPUIndexBuf_Check(v) (Py_TYPE(v) == &BPyGPUIndexBuf_Type)
 
 typedef struct BPyGPUIndexBuf {
-	PyObject_VAR_HEAD
-	struct GPUIndexBuf *elem;
+  PyObject_VAR_HEAD struct GPUIndexBuf *elem;
 } BPyGPUIndexBuf;
 
 PyObject *BPyGPUIndexBuf_CreatePyObject(struct GPUIndexBuf *elem);