Enable "sync -c" default for repo

There's no need to fetch every single branch

Change-Id: I48861c2b46e5d9d94c478fa78e2724546f71ddf1

default.xml

@@ -17,6 +17,7 @@
 
   <default revision="refs/tags/android-4.4_r1"
            remote="aosp"
+           sync-c="true"
            sync-j="4" />
 
   <project path="build" name="android_build" remote="omnirom" revision="android-4.4" groups="pdk" >