Fix building on Solaris x86-64.

sb-unix:unix-select used macros which expanded into many forms,
limited by sb-unix:fd-setsize, which on Solaris-x86-64 is 65536, as
opposed to 1024 on Linux. This resulted in long compile times which
were likely to exhaust the heap.
Use functions instead of macros.
PPRINT (setf . a) correctly.

It was printed as (setf a).

Reported by Douglas Katzman.
Fix floating point exceptions persisting on Solaris.

(/ 0d0 0d0)
(cosh 90)

signaled an invalid-operation exception, and not overflow, on COSH,
because the previous error wasn't cleared. Clear the exception flags
in the sigfpe handler.
tests/run-compiler.sh: use gcc, not cc.
tests/subr.sh: Fix sed invocation for Solaris.