Split atomic and mutex implementations and make inlinable.

include/core/SkRefCnt.h

Index: include/core/SkRefCnt.h
===================================================================
--- include/core/SkRefCnt.h	(revision 12696)
+++ include/core/SkRefCnt.h	(working copy)
@@ -50,7 +50,7 @@
     bool unique() const {
         bool const unique = (1 == fRefCnt);
         if (unique) {
-            // Aquire barrier (L/SL), if not provided by load of fRefCnt.
+            // Acquire barrier (L/SL), if not provided by load of fRefCnt.
             // Prevents user's 'unique' code from happening before decrements.
             //TODO: issue the barrier.
         }
@@ -72,9 +72,9 @@
         SkASSERT(fRefCnt > 0);
         // Release barrier (SL/S), if not provided below.
         if (sk_atomic_dec(&fRefCnt) == 1) {
-            // Aquire barrier (L/SL), if not provided above.
+            // Acquire barrier (L/SL), if not provided above.
             // Prevents code in dispose from happening before the decrement.
-            sk_membar_aquire__after_atomic_dec();
+            sk_membar_acquire__after_atomic_dec();
             internal_dispose();
         }
     }