Add experiment ext-qm

The intention is to add more flexibility in aom-qm.

Change-Id: Ib89f5d396924876180dc4db13ef6cb1b56d94930

build/cmake/aom_config_defaults.cmake

diff --git a/build/cmake/aom_config_defaults.cmake b/build/cmake/aom_config_defaults.cmake
index 488582d..8374c35 100644
--- a/build/cmake/aom_config_defaults.cmake
+++ b/build/cmake/aom_config_defaults.cmake
@@ -140,6 +140,7 @@
 set(CONFIG_EXT_PARTITION 1 CACHE NUMBER "AV1 experiment flag.")
 set(CONFIG_EXT_PARTITION_TYPES 1 CACHE NUMBER "AV1 experiment flag.")
 set(CONFIG_EXT_PARTITION_TYPES_AB 0 CACHE NUMBER "AV1 experiment flag.")
+set(CONFIG_EXT_QM 0 CACHE NUMBER "AV1 experiment flag.")
 set(CONFIG_EXT_SKIP 0 CACHE NUMBER "AV1 experiment flag.")
 set(CONFIG_EXT_TILE 0 CACHE NUMBER "AV1 experiment flag.")
 set(CONFIG_EXT_WARPED_MOTION 0 CACHE NUMBER "AV1 experiment flag.")

configure

diff --git a/configure b/configure
index 561f6fb..685b6b0 100755
--- a/configure
+++ b/configure
@@ -309,6 +309,7 @@
     new_multisymbol
     compound_singleref
     aom_qm
+    ext_qm
     ext_comp_refs
     smooth_hv
     bgsprite