Split atomic and mutex implementations and make inlinable.

src/ports/SkAtomics_none.h

+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkAtomics_none_DEFINED
+#define SkAtomics_none_DEFINED
+
+/** Non-atomic atomics for uniprocessor systems. */
+
+#include <stdint.h>
+
+static inline int32_t sk_atomic_inc(int32_t* addr) {
+    int32_t value = *addr;
+    *addr = value + 1;
+    return value;
+}
+
+static inline int32_t sk_atomic_add(int32_t* addr, int32_t inc) {
+    int32_t value = *addr;
+    *addr = value + inc;
+    return value;
+}
+
+static inline int32_t sk_atomic_dec(int32_t* addr) {
+    int32_t value = *addr;
+    *addr = value - 1;
+    return value;
+}
+
+static inline void sk_membar_acquire__after_atomic_dec() { }
+
+static inline int32_t sk_atomic_conditional_inc(int32_t* addr) {
+    int32_t value = *addr;
+    if (value != 0) ++*addr;
+    return value;
+}
+
+static inline void sk_membar_acquire__after_atomic_conditional_inc() { }
+
+#endif