Disable quartus_sh message output buffering

The problem isn't with the log or the project file. The problem is that when Quartus writes to stdout and stderr, it does so in a buffered fashion. I want the buffer to be flushed more often. We have seen similar problems with other tools before (notably Cadence Xcelium) and sometimes there is a flag to enable unbuffered writes to stdout/stderr.

It's not really a huge issue, just annoying from a regression flow perspective.