Split atomic and mutex implementations and make inlinable.

src/ports/SkAtomics_android.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_android_DEFINED
+#define SkAtomics_android_DEFINED
+
+/** Android framework atomics. */
+
+#include <cutils/atomic.h>
+#include <stdint.h>
+
+#define sk_atomic_inc(addr)         android_atomic_inc(addr)
+#define sk_atomic_add(addr, inc)    android_atomic_add(inc, addr)
+#define sk_atomic_dec(addr)         android_atomic_dec(addr)
+
+static inline __attribute__((always_inline)) void sk_membar_acquire__after_atomic_dec() {
+    //HACK: Android is actually using full memory barriers.
+    //      Should this change, uncomment below.
+    //int dummy;
+    //android_atomic_acquire_store(0, &dummy);
+}
+
+static inline __attribute__((always_inline)) int32_t sk_atomic_conditional_inc(int32_t* addr) {
+    while (true) {
+        int32_t value = *addr;
+        if (value == 0) {
+            return 0;
+        }
+        if (0 == android_atomic_release_cas(value, value + 1, addr)) {
+            return value;
+        }
+    }
+}
+
+static inline __attribute__((always_inline)) void sk_membar_acquire__after_atomic_conditional_inc() {
+    //HACK: Android is actually using full memory barriers.
+    //      Should this change, uncomment below.
+    //int dummy;
+    //android_atomic_acquire_store(0, &dummy);
+}
+
+#endif