[ffigen] Avoid errors in C header file (#1951)

Upstreaming a patch from somewhere downstream

Author: dcharkes

pkgs/ffigen/test/header_parser_tests/globals.h

@@ -2,24 +2,22 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-#include <stdint.h>
 #include <stdbool.h>
+#include <stdint.h>
 
 bool coolGlobal;
 int32_t myInt;
 int32_t *aGlobalPointer0;
-int32_t *const aGlobalPointer1;
+int32_t *const aGlobalPointer1 = nullptr;
 const int32_t *aGlobalPointer2;
-const int32_t *const aGlobalPointer3;
+const int32_t *const aGlobalPointer3 = nullptr;
 long double longDouble;
 long double *pointerToLongDouble;
 
 // This should be ignored
 int GlobalIgnore;
 
-struct EmptyStruct
-{
-};
+struct EmptyStruct {};
 
 struct EmptyStruct globalStruct;