Add ALTREF ref frame into ref_mode_set_reduced

For RTC speed >= 9, ref_mode_set_reduced is used to specify the testing modes and ref frames, but ALTREF is not tested by the configuration of current ref_mode_set_reduced.

This wasn't an issue in current speed feature setup because ALTREF as a single reference frame is turned off when speed >= 8, but it will potentially be an issue if someone wants to change the reference structure (i.e., turn on ALTREF as a single ref frame at speed >= 8).

No behaviour change for speed = 7/8/9/10 for rtc set based on our current reference structure setup.

Change-Id: Idd9f1bff936be8d6591574858d09b4f3a81044fe
diff --git a/av1/encoder/nonrd_pickmode.c b/av1/encoder/nonrd_pickmode.c
index 23e1a7b..c41bd79 100644
--- a/av1/encoder/nonrd_pickmode.c
+++ b/av1/encoder/nonrd_pickmode.c
@@ -82,7 +82,7 @@
 
 #define NUM_INTER_MODES_RT 9
 #define NUM_COMP_INTER_MODES_RT (6)
-#define NUM_INTER_MODES_REDUCED 8
+#define NUM_INTER_MODES_REDUCED 12
 
 static const REF_MODE ref_mode_set_rt[NUM_INTER_MODES_RT] = {
   { LAST_FRAME, NEARESTMV },   { LAST_FRAME, NEARMV },
@@ -99,6 +99,8 @@
   { LAST_FRAME, GLOBALMV },    { LAST_FRAME, NEWMV },
   { GOLDEN_FRAME, NEARESTMV }, { GOLDEN_FRAME, NEARMV },
   { GOLDEN_FRAME, GLOBALMV },  { GOLDEN_FRAME, NEWMV },
+  { ALTREF_FRAME, NEARESTMV }, { ALTREF_FRAME, NEARMV },
+  { ALTREF_FRAME, GLOBALMV },  { ALTREF_FRAME, NEWMV },
 };
 
 static const COMP_REF_MODE comp_ref_mode_set[NUM_COMP_INTER_MODES_RT] = {