Enable VP10 by default

Since VP10 is now the only codec supported.

Change-Id: I3226dceacb87f422f87c9f4af06c73a254143436

configure

diff --git a/configure b/configure
index 7d160e7..288a2bf 100755
--- a/configure
+++ b/configure
@@ -195,9 +195,6 @@
 # disable codecs when their source directory does not exist
 [ -d "${source_path}/vp10" ] || disable_feature vp10
 
-# disable vp10 codec by default
-disable_feature vp10
-
 # install everything except the sources, by default. sources will have
 # to be enabled when doing dist builds, since that's no longer a common
 # case.