fail the build on outdated .sha1 files

branch_4x (only) currently has the following outdated/leftover .sha1s from obselete versions:

$ svn status
!       solr/licenses/junit4-ant-2.0.0.rc5.jar.sha1
!       solr/licenses/randomizedtesting-runner-2.0.0.rc5.jar.sha1

This is easy enough to implement. just run 'ant jar-checksums' before our svn status check.