Fix Flutter/Fushcia build

Bug: skia:
Change-Id: I17d65cef0dea11b23c935a367f3ac63d50156e15
Reviewed-on: https://skia-review.googlesource.com/69880
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/GrOpList.h b/src/gpu/GrOpList.h
index d41b940..8e9babd 100644
--- a/src/gpu/GrOpList.h
+++ b/src/gpu/GrOpList.h
@@ -15,10 +15,14 @@
 
 
 // Turn on/off the explicit distribution of GPU resources at flush time
-#define SK_DISABLE_EXPLICIT_GPU_RESOURCE_ALLOCATION
+#ifndef SK_DISABLE_EXPLICIT_GPU_RESOURCE_ALLOCATION
+   #define SK_DISABLE_EXPLICIT_GPU_RESOURCE_ALLOCATION
+#endif
 
 // Turn on/off the sorting of opLists at flush time
-#define SK_DISABLE_RENDER_TARGET_SORTING
+#ifndef SK_DISABLE_RENDER_TARGET_SORTING
+   #define SK_DISABLE_RENDER_TARGET_SORTING
+#endif
 
 class GrAuditTrail;
 class GrCaps;