Drop support for non-atomic non-mutex platforms.

src/ports/SkAtomics_none.h

Index: src/ports/SkAtomics_none.h
diff --git a/src/ports/SkAtomics_none.h b/src/ports/SkAtomics_none.h
deleted file mode 100644
index 73cbf0af2253498974dacaf9145a3cf3bb965121..0000000000000000000000000000000000000000
--- a/src/ports/SkAtomics_none.h
+++ /dev/null
@@ -1,43 +0,0 @@
-/*
- * 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 bool sk_atomic_cas(int32_t* addr, int32_t before, int32_t after) {
-    if (*addr != before) return false;
-    *addr = after;
-    return true;
-}
-
-static inline void sk_membar_acquire__after_atomic_conditional_inc() { }
-
-#endif