Bug 16141 workaround and set better parallel configs

Hi!

On the following of my email today to cling-dev, this should work like a workaround to the [Bug 16141](http://llvm.org/bugs/show_bug.cgi?id=16141) that Axel pointed out.

Also, I added a little hack to improve paralelism in `make`, so "make" will use has much "jobs" as processors in the machine.

Cheers,

Rafael