On systems without SIGALRM, the other features of eval-in-sandbox
may still be useful. This adds the option to set #:time-limit to
#f to indicate no timeout.
* NEWS: updated
* module/ice-9/sandbox.scm (eval-in-sandbox): allow #:time-limit key
to be #f to disable time limit
* doc/ref/api-evaluation.texi (eval-in-sandbox): update documentation
* test-suite/tests/sandbox.scm ("eval-in-sandbox"): throw unsupported
if no SIGALARM
("eval-in-sandbox no timeout"): new tests for eval-in-sandbox