GHC 6.4.3 on FreeBSD

[Simon Marlow]

An update on the GHC/FreeBSD front: I didn't manage to reproduce the
reported threading bugs on a UP, will be trying on a MP shortly.  

However, I did discover one odd case that libpthread doesn't appear to
handle properly, but libthr does.  This arose from a test in GHC's test
suite, but I've transliterated the code from Haskell to C:

$ cat thr1.c 
#include <unistd.h>
#include <signal.h>
#include <pthread.h>

int main(int argc, char *argv[])
{
    sigset_t s;

    sigemptyset (&s);
    sigaddset(&s, SIGUSR1);
    sigprocmask(SIG_BLOCK, &s, NULL);
    pthread_kill(pthread_self(), SIGUSR1);
    sigpending(&s);
    printf("%x\n", s);
    exit(0);
}
$ gcc -pthread thr1.c
$ ./a.out
0
$ gcc -lthr thr1.c
$ ./a.out
20000000
$ 

This might (or might not) be related to the other threading issues with
GHC on FreeBSD.

Do you think we should link with -lthr by default on FreeBSD?  This
would be a trivial change to make, and given that GHC has its own
lightweight threading runtime, we probably aren't getting much from
having the KSE-based threading implementation anyway.

Cheers,
	Simon