Removed build dependency on er_tables_xor.h, since it has been deleted

As part of https://webrtc-codereview.appspot.com/45899004/ the file er_tables_xor.h was removed, but not its dependencies in .gn and .gypi.

BUG=N/A
TBR=pbos

Review URL: https://webrtc-codereview.appspot.com/48889004

Cr-Commit-Position: refs/heads/master@{#8944}
diff --git a/webrtc/modules/video_coding/BUILD.gn b/webrtc/modules/video_coding/BUILD.gn
index 4bcbe29..340a203 100644
--- a/webrtc/modules/video_coding/BUILD.gn
+++ b/webrtc/modules/video_coding/BUILD.gn
@@ -22,7 +22,6 @@
     "main/source/decoding_state.h",
     "main/source/encoded_frame.cc",
     "main/source/encoded_frame.h",
-    "main/source/er_tables_xor.h",
     "main/source/fec_tables_xor.h",
     "main/source/frame_buffer.cc",
     "main/source/frame_buffer.h",
diff --git a/webrtc/modules/video_coding/video_coding.gypi b/webrtc/modules/video_coding/video_coding.gypi
index 484b82a..fd9d37d 100644
--- a/webrtc/modules/video_coding/video_coding.gypi
+++ b/webrtc/modules/video_coding/video_coding.gypi
@@ -30,7 +30,6 @@
         'main/source/content_metrics_processing.h',
         'main/source/decoding_state.h',
         'main/source/encoded_frame.h',
-        'main/source/er_tables_xor.h',
         'main/source/fec_tables_xor.h',
         'main/source/frame_buffer.h',
         'main/source/generic_decoder.h',