Force libphonenumber to continue to use v51 (1.7) .class files

The default is changing to v52 (1.8).

The build for this package uses jarjar to repackage .class files.

The version of jarjar in the Android tree does not currently
support v52 .class files.

Bug: 26753820
(cherry picked from commit 365cb132aed0abe6f0bc60ebd014f0d1f8dc9d5c)

Change-Id: I1fd9d8883d32fb4d69c97730507a5c3bae85b45a
1 file changed