Preopt apps with updatable boot classpath too.

Test: m
Test: egrep 'ethernet-service[^ ]*odex' out/soong/build.ninja \
    | grep updatable
  # is empty
  egrep 'oat-file=[^ ]*Gallery2[^ ]*odex' out/soong/build.ninja \
    | egrep -o 'Xbootclasspath:[^ ]*' \
    | sed 's/:/\n/g' \
    | grep updatable_bootjars
  # lists updatable boot jars
  egrep -o 'Xbootclasspath:[^ ]*' \
      -o `find out -name dexpreopt.sh | grep Dialer` \
    | sed 's/:/\n/g' \
    | grep updatable_bootjars
  # lists updatable boot jars
Bug: 178467404
Change-Id: Ia5d4e59bac3e32bc77f1a0ab9e1abb18768a7ee7