Separate core and images project.

include/images/SkForceLinking.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.
+ */
+
+/**
+ *  This function's sole purpose is to trick the linker into not discarding
+ *  SkImageDecoder subclasses just because we do not directly call them.
+ *  This is necessary in applications that will create image decoders from
+ *  a stream.
+ *  Call this function with an expression that evaluates to false to ensure
+ *  that the linker includes the subclasses.
+ *  Passing true will result in leaked objects.
+ */
+int SkForceLinking(bool doNotPassTrue);
+
+#define __SK_FORCE_IMAGE_DECODER_LINKING       \
+static int linking_forced = SkForceLinking(false)