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

intern/cycles/util/util_algorithm.h

@@ -21,12 +21,12 @@
 
 CCL_NAMESPACE_BEGIN
 
-using std::sort;
-using std::swap;
 using std::max;
 using std::min;
 using std::remove;
+using std::sort;
+using std::swap;
 
 CCL_NAMESPACE_END
 
-#endif  /* __UTIL_ALGORITHM_H__ */
+#endif /* __UTIL_ALGORITHM_H__ */