Fix #86: Make cmucl work with gcc 8.1.1 and later

In alloc(), save the fpu state on entry to the function and restore it
just before returning.  

While we're at it, use the __attribute__ option to get a 16-byte
aligned area where we can save the fpu state.

And also set optimization to -O2 for linux.
2 jobs for issue-86-save-fpu-state-on-entry-to-alloc in 8 minutes and 43 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Test
failed linux-runner #4201
linux

00:01:29

passed osx-runner #4202
osx

00:08:43

 
Name Stage Failure
failed
linux-runner Test
No job log