Remove interp filter for non-translation global mv

BDRATE results:
lowres: -0.880% (up from -0.844%)

Change-Id: I017c0beddcc687148fed33c1e9963e05f1eaf6ea
diff --git a/av1/encoder/bitstream.c b/av1/encoder/bitstream.c
index 9dce985..3340906 100644
--- a/av1/encoder/bitstream.c
+++ b/av1/encoder/bitstream.c
@@ -1148,6 +1148,9 @@
   FRAME_CONTEXT *ec_ctx = cm->fc;
 #endif
 
+#if CONFIG_GLOBAL_MOTION
+  if (is_nontrans_global_motion(xd)) return;
+#endif  // CONFIG_GLOBAL_MOTION
   if (cm->interp_filter == SWITCHABLE) {
 #if CONFIG_DUAL_FILTER
     int dir;
@@ -1518,7 +1521,7 @@
       }
     }
 
-#if !CONFIG_DUAL_FILTER && !CONFIG_WARPED_MOTION
+#if !CONFIG_DUAL_FILTER && !CONFIG_WARPED_MOTION && !CONFIG_GLOBAL_MOTION
     write_mb_interp_filter(cpi, xd, w);
 #endif  // !CONFIG_DUAL_FILTER && !CONFIG_WARPED_MOTION
 
@@ -1715,7 +1718,7 @@
 #if CONFIG_WARPED_MOTION
     if (mbmi->motion_mode != WARPED_CAUSAL)
 #endif  // CONFIG_WARPED_MOTION
-#if CONFIG_DUAL_FILTER || CONFIG_WARPED_MOTION
+#if CONFIG_DUAL_FILTER || CONFIG_WARPED_MOTION || CONFIG_GLOBAL_MOTION
       write_mb_interp_filter(cpi, xd, w);
 #endif  // CONFIG_DUAL_FILTE || CONFIG_WARPED_MOTION
   }