Pin libraries needed by vogar tool to java 1.7

vogar still uses javac/dx by default. dx does not
handle v52 class files. The default java version
is going to switch to 1.8. This change pins the
targets need by vogar to 1.7.

Bug: 26753820
Bug: 27310428
(cherry picked from commit 8238dc2d015b4d44bdac5c9a25befdd42eae0663)

Change-Id: Id40b5d2fe475b5ca50162b75f018b31a98cddf4f