[Cbc] muti-thread compile for cbc-2.7.8

[Noli Sicad]

Upgraded to gcc 4.7.2.

The problem is the trunk code that I placed in the cbc-2.7.8. I was
after on the new heuristic proximity.

The other day, I realized that proximity code were already merged
before the release.

Compiling the clean cbc-2.7.8 is working with threads.

My macbookpro is running crazy, the fans is running and all the 8
threads are used.

I got amazing results with threads and proximity on.

Previously, my MIP model was solved with "proximity on" in 28m14.947s.

Now with -threads 8 and proximity on, the same MIP model is solved in
1m17.377s. The fan is working and the cpu % between 618% to 694%
usage.

Using Htop, you can see that all the 8 threads at 100%.

Noli