devel/bcc: mark BROKEN, unfetchable

Something obviously changed within the framework, but I'm confused
how MASTER_SITES was never defined for bcc:

> bcc-1995.03.12_1 depends on file: /usr/local/sbin/pkg - found

> bcc.tar.gz doesn't seem to exist in /distfiles/.

> /!\ Warning /!\

The :DEFAULT group used for bcc.tar.gz is missing
from MASTER_SITES. Check for typos, or errors.

> Couldn't fetch it - please try to retrieve this

> port manually into /distfiles/ and try again.

• Error code 1

Strangely it's an Warning on FreeBSD 10.3 and an Error on DF. The
result is the same though: impossible to fetch.