fix [2170898] abort() doesn't print a stack tarce

the issue here is that abort() can be called from anywhere, in particular
from malloc or free. When we try to use the debug_log functions, these
can end up calling into some code (like malloc/free) that called abort()
in the first place and end up in an infinite recursion loop.

libc/unistd/abort.c

@@ -73,10 +73,8 @@ abort(void)
 	}
 
     /* temporary, for bug hunting */
-    debug_log("abort() called in pid %d\n", getpid());
     /* seg fault seems to produce better debuggerd results than SIGABRT */
     *((char*)0xdeadbaad) = 39;
-    debug_log("somehow we're not dead?\n");
     /* -- */
 
 	(void)kill(getpid(), SIGABRT);