Make.pkg: have "make coverage" invoke 6cov with correct binary
Make.pkg: have "make coverage" invoke 6cov with correct binary

Fixes issue 239.

R=r
http://codereview.appspot.com/154176
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go