av1_collect_motion_search_features_sb: add missing alloc checks

Bug: aomedia:3276
Change-Id: I6bb1efb546607f4a3069ce6ae8b6418e7e818b67
diff --git a/av1/encoder/partition_strategy.c b/av1/encoder/partition_strategy.c
index ed1b43a..86d4b9b 100644
--- a/av1/encoder/partition_strategy.c
+++ b/av1/encoder/partition_strategy.c
@@ -2423,6 +2423,13 @@
   const int num_blocks = col_steps * row_steps;
   unsigned int *block_sse = aom_calloc(num_blocks, sizeof(*block_sse));
   unsigned int *block_var = aom_calloc(num_blocks, sizeof(*block_var));
+  if (!(block_sse && block_var)) {
+    aom_free(sms_tree);
+    aom_free(block_sse);
+    aom_free(block_var);
+    aom_internal_error(cm->error, AOM_CODEC_MEM_ERROR,
+                       "Error allocating block_sse & block_var");
+  }
   int idx = 0;
 
   for (int row = mi_row;