Run clang-format on all files

The main change here is to reorder headers.

src/wcstringutil.cpp

@@ -1,11 +1,12 @@
 // Helper functions for working with wcstring.
 #include "config.h"  // IWYU pragma: keep
 
-#include "common.h"
 #include "wcstringutil.h"
 
 #include <wctype.h>
 
+#include "common.h"
+
 typedef wcstring::size_type size_type;
 
 wcstring_range wcstring_tok(wcstring &str, const wcstring &needle, wcstring_range last) {