Eliminate SkFILE - it always is the same as FILE.

src/ports/SkOSFile_posix.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkOSFile.h"
 #include "SkString.h"
 #include "SkTFitsIn.h"
@@ skipping 17 matching lines @@
         mode |= W_OK;
     }
     return (0 == access(path, mode));
 }
 
 typedef struct {
     dev_t dev;
     ino_t ino;
 } SkFILEID;
 
-static bool sk_ino(SkFILE* a, SkFILEID* id) {
-    int fd = fileno((FILE*)a);
+static bool sk_ino(FILE* a, SkFILEID* id) {
+    int fd = fileno(a);
     if (fd < 0) {
         return 0;
     }
     struct stat status;
     if (0 != fstat(fd, &status)) {
         return 0;
     }
     id->dev = status.st_dev;
     id->ino = status.st_ino;
     return true;
 }
 
-bool sk_fidentical(SkFILE* a, SkFILE* b) {
+bool sk_fidentical(FILE* a, FILE* b) {
     SkFILEID aID, bID;
     return sk_ino(a, &aID) && sk_ino(b, &bID)
            && aID.ino == bID.ino
            && aID.dev == bID.dev;
 }
 
 void sk_fmunmap(const void* addr, size_t length) {
     munmap(const_cast<void*>(addr), length);
 }
 
@@ skipping 12 matching lines @@
 
     void* addr = mmap(nullptr, fileSize, PROT_READ, MAP_PRIVATE, fd, 0);
     if (MAP_FAILED == addr) {
         return nullptr;
     }
 
     *size = fileSize;
     return addr;
 }
 
-int sk_fileno(SkFILE* f) {
-    return fileno((FILE*)f);
+int sk_fileno(FILE* f) {
+    return fileno(f);
 }
 
-void* sk_fmmap(SkFILE* f, size_t* size) {
+void* sk_fmmap(FILE* f, size_t* size) {
     int fd = sk_fileno(f);
     if (fd < 0) {
         return nullptr;
     }
 
     return sk_fdmmap(fd, size);
 }
 
 ////////////////////////////////////////////////////////////////////////////
 
@@ skipping 72 matching lines @@
         }
         if (entry) { // we broke out with a file
             if (name) {
                 name->set(entry->d_name);
             }
             return true;
         }
     }
     return false;
 }