Split atomic and mutex implementations and make inlinable.

src/ports/SkThread_none.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 "SkThread.h"
-
-int32_t sk_atomic_inc(int32_t* addr) {
-    int32_t value = *addr;
-    *addr = value + 1;
-    return value;
-}
-
-int32_t sk_atomic_add(int32_t* addr, int32_t inc) {
-    int32_t value = *addr;
-    *addr = value + inc;
-    return value;
-}
-
-int32_t sk_atomic_dec(int32_t* addr) {
-    int32_t value = *addr;
-    *addr = value - 1;
-    return value;
-}
-void sk_membar_aquire__after_atomic_dec() { }
-
-int32_t sk_atomic_conditional_inc(int32_t* addr) {
-    int32_t value = *addr;
-    if (value != 0) ++*addr;
-    return value;
-}
-void sk_membar_aquire__after_atomic_conditional_inc() { }
-
-SkMutex::SkMutex() {}
-
-SkMutex::~SkMutex() {}
-
-#ifndef SK_USE_POSIX_THREADS
-void SkMutex::acquire() {}
-void SkMutex::release() {}
-#endif