GrRedBlackTree test is GPU specific.

Wrapp the entire file/test in a SK_SUPPORT_GPU.

This should fix the tree breakage.

BUG=None
TEST=tests
TBR=robertphillips@google.com

Review URL: https://codereview.chromium.org/147843006

git-svn-id: http://skia.googlecode.com/svn/trunk@13234 2bbb7eff-a529-9590-31e7-b0007b416f81

tests/GrRedBlackTreeTest.cpp

@@ -5,6 +5,9 @@
  * found in the LICENSE file.
  */
 
+// This is a GPU-backend specific test
+#if SK_SUPPORT_GPU
+
 #include "GrRedBlackTree.h"
 #include "SkRandom.h"
 #include "Test.h"
@@ -178,3 +181,5 @@ DEF_TEST(GrRedBlackTreeTest, reporter) {
     // test reset on empty tree.
     tree.reset();
 }
+
+#endif