vpxenc: add --aq-mode flag to control adaptive quantization

Change-Id: I57e1ad4bed3487df12893ced77c49093f8755706
diff --git a/vpxenc.c b/vpxenc.c
index b7897db..674da14 100644
--- a/vpxenc.c
+++ b/vpxenc.c
@@ -561,6 +561,9 @@
 #if CONFIG_VP9_ENCODER
 static const arg_def_t frame_parallel_decoding  = ARG_DEF(
     NULL, "frame-parallel", 1, "Enable frame parallel decodability features");
+static const arg_def_t aq_mode  = ARG_DEF(
+    NULL, "aq-mode", 1,
+    "Adaptive quantization mode (0: disabled (by default), 1: variance based)");
 #endif
 
 #if CONFIG_VP8_ENCODER
@@ -585,7 +588,7 @@
   &cpu_used, &auto_altref, &noise_sens, &sharpness, &static_thresh,
   &tile_cols, &tile_rows, &arnr_maxframes, &arnr_strength, &arnr_type,
   &tune_ssim, &cq_level, &max_intra_rate_pct, &lossless,
-  &frame_parallel_decoding,
+  &frame_parallel_decoding, &aq_mode,
   NULL
 };
 static const int vp9_arg_ctrl_map[] = {
@@ -594,7 +597,7 @@
   VP9E_SET_TILE_COLUMNS, VP9E_SET_TILE_ROWS,
   VP8E_SET_ARNR_MAXFRAMES, VP8E_SET_ARNR_STRENGTH, VP8E_SET_ARNR_TYPE,
   VP8E_SET_TUNING, VP8E_SET_CQ_LEVEL, VP8E_SET_MAX_INTRA_BITRATE_PCT,
-  VP9E_SET_LOSSLESS, VP9E_SET_FRAME_PARALLEL_DECODING,
+  VP9E_SET_LOSSLESS, VP9E_SET_FRAME_PARALLEL_DECODING, VP9E_SET_AQ_MODE,
   0
 };
 #endif