Add frame_marker experimental flag

The frame index in natural display order is needed by several
experiments, hence move it as a root experiment. The additional
overhead cost associated with frame_marker is below 0.05% level.

Change-Id: Ie643a6bc1f5a400ea6ff088751a676bb56ffee76
diff --git a/configure b/configure
index 4351a55..d427a78 100755
--- a/configure
+++ b/configure
@@ -347,6 +347,7 @@
     hash_me
     colorspace_headers
     mfmv
+    frame_marker
     jnt_comp
     obu
     amvr
@@ -569,6 +570,8 @@
     enabled cfl && enable_feature smooth_hv
     enabled cdef_singlepass && enable_feature cdef
     enabled new_multisymbol && enable_feature restrict_compressed_hdr
+    enabled mfmv && enable_feature frame_marker
+    enabled jnt_comp && enable_feature frame_marker
 
     if enabled rawbits && enabled ans; then
       log_echo "rawbits requires not ans, so disabling rawbits"