irssi: inherit user cflags
mesalib: depends on msgfmt
musl: fix bug in synccall

this bug caused irssi to deadlock when changing its configuration,
for example by doing /set server_reconnect_time 10sec .
(this caused a piece of code at core.c:100 to be executed
which called setprlimit), but only when a preloaded process (such
as proxychains) was spawning a thread so libc would take the
libc.thread_minus_1 > 0 code path.

compiling the below code to a .so and preloading it would also
cause the bug

 #include <unistd.h>
 #include <pthread.h>

static void* thread(void* arg) {
	while(1) sleep(10000);
}

__attribute__ ((constructor))
static void gcc_init(void)
{
	pthread_t sleeper;
	pthread_create(&sleeper, 0, thread, 0);
}