[distcc] small protocol extensions for -ftest-coverage, -fbranch-probabilities

[Daniel Kegel]

Anyone working on adding support for sending the .bb and .bbg files
generated by the compiler on -ftest-coverage from the server back to the client,
or sending the .da files for -fbranch-probabilities from the client to the server?

Three new tokens would need to be added to the protocol:
if -ftest-coverage is given, DOBB and DBBG tokens would be sent back from the
server before DOTO;
if -fbranch-probabilities is given, a DODA token would be sent to the server
right before the DOTI,
but that's about it, I think.

(Making sure the .da files get the right embedded path will be a bit tricky;
it'll probably require a small patch to gcc.  But hey, I'm not scared of that :-)

Comments?
- Dan