David Lechner 3bd2ae1a36 unix/mpthreadport: Use SIGRTMIN+5 instead of SIGUSR1 for thread-GC.
This changes the signal used to trigger garbage collection from SIGUSR1 to
SIGRTMIN + 5.  SIGUSR1 is quite common compared to SIGRTMIN (measured by
google search results) and is more likely to conflict with libraries that
may use the same signal.

POSIX specifies that there are at least 8 real-time signal so 5 was chosen
as a "random" number to further avoid potential conflict with libraries
that may use SIGRTMIN or SIGRTMAX.

Also, if we ever have a `usignal` module, it would be nice to leave SIGUSR1
and SIGUSR2 free for user programs.
2020-02-18 13:32:42 +11:00
..
2020-02-07 11:24:06 +11:00