fix issues with segment_pred_last

* Proper re-allocation of seg_map buffer when resolution changes
* Remove undesired resetting of seg_map buffer

* This resolves issues raised in

   https://bugs.chromium.org/p/aomedia/issues/detail?id=1064
   https://bugs.chromium.org/p/aomedia/issues/detail?id=1091

* Disable error_resilient_flag in resize_test as this covers more cases

* Will be enabled by default in separate patch

BUG=aomedia:1064
BUG=aomedia:1091

Change-Id: Ic3f0e47922784c66d240b52d30ba082bdb46dc3b
diff --git a/test/resize_test.cc b/test/resize_test.cc
index 3e78c05..0b0915e 100644
--- a/test/resize_test.cc
+++ b/test/resize_test.cc
@@ -483,8 +483,8 @@
     cfg_.kf_min_dist = cfg_.kf_max_dist = 3000;
     // Enable dropped frames.
     cfg_.rc_dropframe_thresh = 1;
-    // Enable error_resilience mode.
-    cfg_.g_error_resilient = 1;
+    // Disable error_resilience mode.
+    cfg_.g_error_resilient = 0;
     // Run at low bitrate.
     cfg_.rc_target_bitrate = 200;
   }