Convert rc_max_intra_bitrate_pct to control

Since this is the only ABI incompatible change since the last release,
convert it to use the control interface instead. The member of the
configuration struct is replaced with the VP8E_SET_MAX_INTRA_BITRATE_PCT
control.

More significant API changes were expected to be forthcoming when this
control was first introduced, and while they continue to be expected,
it's not worth breaking compatibility for only this change.

Change-Id: I799d8dbe24c8bc9c241e0b7743b2b64f81327d59
diff --git a/vpxenc.c b/vpxenc.c
index 2de881c..f0b834a 100644
--- a/vpxenc.c
+++ b/vpxenc.c
@@ -1016,14 +1016,11 @@
         "Client initial buffer size (ms)");
 static const arg_def_t buf_optimal_sz     = ARG_DEF(NULL, "buf-optimal-sz", 1,
         "Client optimal buffer size (ms)");
-static const arg_def_t max_intra_rate_pct = ARG_DEF(NULL, "max-intra-rate", 1,
-        "Max I-frame bitrate (pct)");
 static const arg_def_t *rc_args[] =
 {
     &dropframe_thresh, &resize_allowed, &resize_up_thresh, &resize_down_thresh,
     &end_usage, &target_bitrate, &min_quantizer, &max_quantizer,
     &undershoot_pct, &overshoot_pct, &buf_sz, &buf_initial_sz, &buf_optimal_sz,
-    &max_intra_rate_pct,
     NULL
 };
 
@@ -1087,12 +1084,14 @@
                                    "Material to favor", tuning_enum);
 static const arg_def_t cq_level = ARG_DEF(NULL, "cq-level", 1,
                                    "Constrained Quality Level");
+static const arg_def_t max_intra_rate_pct = ARG_DEF(NULL, "max-intra-rate", 1,
+        "Max I-frame bitrate (pct)");
 
 static const arg_def_t *vp8_args[] =
 {
     &cpu_used, &auto_altref, &noise_sens, &sharpness, &static_thresh,
     &token_parts, &arnr_maxframes, &arnr_strength, &arnr_type,
-    &tune_ssim, &cq_level, NULL
+    &tune_ssim, &cq_level, &max_intra_rate_pct, NULL
 };
 static const int vp8_arg_ctrl_map[] =
 {
@@ -1100,7 +1099,7 @@
     VP8E_SET_NOISE_SENSITIVITY, VP8E_SET_SHARPNESS, VP8E_SET_STATIC_THRESHOLD,
     VP8E_SET_TOKEN_PARTITIONS,
     VP8E_SET_ARNR_MAXFRAMES, VP8E_SET_ARNR_STRENGTH , VP8E_SET_ARNR_TYPE,
-    VP8E_SET_TUNING, VP8E_SET_CQ_LEVEL, 0
+    VP8E_SET_TUNING, VP8E_SET_CQ_LEVEL, VP8E_SET_MAX_INTRA_BITRATE_PCT, 0
 };
 #endif
 
@@ -1639,8 +1638,6 @@
             cfg.rc_end_usage = arg_parse_enum_or_int(&arg);
         else if (arg_match(&arg, &target_bitrate, argi))
             cfg.rc_target_bitrate = arg_parse_uint(&arg);
-        else if (arg_match(&arg, &max_intra_rate_pct, argi))
-            cfg.rc_max_intra_bitrate_pct = arg_parse_uint(&arg);
         else if (arg_match(&arg, &min_quantizer, argi))
             cfg.rc_min_quantizer = arg_parse_uint(&arg);
         else if (arg_match(&arg, &max_quantizer, argi))