Makefile: fix unit test flakehunter when running on specific package
Makefile: fix unit test flakehunter when running on specific package

When using the unit test flakehunter and specifying a package, after the
first successful run, all of the tests would be run, rather than just
the ones within the specified package.

aakselrod/lnd,LightningNetwork/lnd,LightningNetwork/lnd,aakselrod/lnd