Add new experimental flag ext_partition_types_ab

Change-Id: Ib85b2a778e1306444ac0cbbfb212e739a0f0009c

build/cmake/aom_config_defaults.cmake

@@ -141,6 +141,7 @@ set(CONFIG_EXT_INTER 1 CACHE NUMBER "AV1 experiment flag.")
 set(CONFIG_EXT_INTRA 1 CACHE NUMBER "AV1 experiment flag.")
 set(CONFIG_EXT_PARTITION 0 CACHE NUMBER "AV1 experiment flag.")
 set(CONFIG_EXT_PARTITION_TYPES 0 CACHE NUMBER "AV1 experiment flag.")
+set(CONFIG_EXT_PARTITION_TYPES_AB 0 CACHE NUMBER "AV1 experiment flag.")
 set(CONFIG_EXT_REFS 1 CACHE NUMBER "AV1 experiment flag.")
 set(CONFIG_EXT_TILE 0 CACHE NUMBER "AV1 experiment flag.")
 set(CONFIG_EXT_TX 1 CACHE NUMBER "AV1 experiment flag.")

configure

@@ -278,6 +278,7 @@ EXPERIMENT_LIST="
     loop_restoration
     ext_partition
     ext_partition_types
+    ext_partition_types_ab
     unpoison_partition_ctx
     ext_tile
     motion_var