Don't require -DSK_USE_POSIX_THREADS.

src/core/SkPixelRef.cpp

Index: src/core/SkPixelRef.cpp
diff --git a/src/core/SkPixelRef.cpp b/src/core/SkPixelRef.cpp
index a2c37c6e72f92de7ce16d301632dacdb6dbb1fbf..bb4a5eff8882f6127d56ec8a0c9637b02b1639e0 100644
--- a/src/core/SkPixelRef.cpp
+++ b/src/core/SkPixelRef.cpp
@@ -8,8 +8,14 @@
 #include "SkPixelRef.h"
 #include "SkThread.h"
 
-#ifdef SK_USE_POSIX_THREADS
+#ifdef SK_BUILD_FOR_WIN32
+    // We don't have SK_BASE_MUTEX_INIT on Windows.
 
+    // must be a power-of-2. undef to just use 1 mutex
+    #define PIXELREF_MUTEX_RING_COUNT       32
+    static SkBaseMutex gPixelRefMutexRing[PIXELREF_MUTEX_RING_COUNT];
+
+#else
     static SkBaseMutex gPixelRefMutexRing[] = {
         SK_BASE_MUTEX_INIT, SK_BASE_MUTEX_INIT,
         SK_BASE_MUTEX_INIT, SK_BASE_MUTEX_INIT,
@@ -31,16 +37,9 @@
         SK_BASE_MUTEX_INIT, SK_BASE_MUTEX_INIT,
         SK_BASE_MUTEX_INIT, SK_BASE_MUTEX_INIT,
     };
-
     // must be a power-of-2. undef to just use 1 mutex
     #define PIXELREF_MUTEX_RING_COUNT SK_ARRAY_COUNT(gPixelRefMutexRing)
 
-#else // not pthreads
-
-    // must be a power-of-2. undef to just use 1 mutex
-    #define PIXELREF_MUTEX_RING_COUNT       32
-    static SkBaseMutex gPixelRefMutexRing[PIXELREF_MUTEX_RING_COUNT];
-
 #endif
 
 static SkBaseMutex* get_default_mutex() {