Add tpl_mv experiment flag

Add temporal motion vector referencing experiment flag.

Change-Id: I9a0fced67f4f94071bd6a38eacf9e4f311099c79
diff --git a/configure b/configure
index eb42b0e..8ee3ae8 100755
--- a/configure
+++ b/configure
@@ -255,6 +255,7 @@
     var_tx
     rect_tx
     ref_mv
+    tpl_mv
     dual_filter
     convolve_round
     ext_tx