setitimer with Cygwin and Hurd

[Mike Gran]

Hi-
In trying to get Guile master to build on a few
different VMs, I've run into a problem with setitimer and
getitimer for ITIMER_PROF and ITIMER_VIRTUAL.
On Hurd, calls to setitimer and getitimer for the profiling
and virtual timers will always fail with ENOSYS.
On Cygwin, calls to setitimer and getitimer for the
profiling and virtual timers will always fail with EINVAL.
I figure the way forward is to patch the test suite
so that any tests that require the profiling or virtual
itimers is 'unsupported.  But you'd end up with quite a
bit of special casing in a half-dozen of the test scripts.
Anyone have a better suggestion?
-Mike Gran