Move GrFixedClip into src directory

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2254343003

Review-Url: https://codereview.chromium.org/2254343003
diff --git a/src/gpu/batches/GrMSAAPathRenderer.cpp b/src/gpu/batches/GrMSAAPathRenderer.cpp
index 05a23a1..d6b5578 100644
--- a/src/gpu/batches/GrMSAAPathRenderer.cpp
+++ b/src/gpu/batches/GrMSAAPathRenderer.cpp
@@ -11,6 +11,7 @@
 #include "GrBatchFlushState.h"
 #include "GrClip.h"
 #include "GrDefaultGeoProcFactory.h"
+#include "GrFixedClip.h"
 #include "GrPathStencilSettings.h"
 #include "GrPathUtils.h"
 #include "GrPipelineBuilder.h"