Clean up a few includes, introduce iwyu.

src/ports/SkOSFile_stdio.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkOSFile.h"
+#include "SkTypes.h"
 
 #include <errno.h>
 #include <stdio.h>
 #include <sys/stat.h>
-#include <sys/types.h>
 
 #ifdef _WIN32
 #include <direct.h>
 #include <io.h>
 #endif
 
 SkFILE* sk_fopen(const char path[], SkFILE_Flags flags) {
     char    perm[4];
     char*   p = perm;
 
@@ skipping 122 matching lines @@
 #else
     retval = mkdir(path, 0777);
 #endif
     if (0 == retval) {
         return true;
     } else {
         fprintf(stderr, "sk_mkdir: error %d creating dir '%s'\n", errno, path);
         return false;
     }
 }