Fix raw exit_group(2) decoding

* syscall.c (trace_syscall_entering): Check for sys_exit instead of
SYS_exit to handle exit_group(2) as well as _exit(2).
diff --git a/syscall.c b/syscall.c
index 79d3b4a..e66ac0a 100644
--- a/syscall.c
+++ b/syscall.c
@@ -2707,7 +2707,8 @@
 	else
 		tprintf("%s(", sysent[tcp->scno].sys_name);
 	if (tcp->scno >= nsyscalls || tcp->scno < 0 ||
-	    ((qual_flags[tcp->scno] & QUAL_RAW) && tcp->scno != SYS_exit))
+	    ((qual_flags[tcp->scno] & QUAL_RAW) &&
+	     sysent[tcp->scno].sys_func != sys_exit))
 		sys_res = printargs(tcp);
 	else
 		sys_res = (*sysent[tcp->scno].sys_func)(tcp);