Fix MIPS sys_clone

The clone syscall takes 6 args.

Signed-off-by: Paul Brook <paul@codesourcery.com>
diff --git a/linux-user/main.c b/linux-user/main.c
index 7eabd0c..7348447 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -1626,7 +1626,7 @@
 	MIPS_SYS(sys_ipc		, 6)
 	MIPS_SYS(sys_fsync	, 1)
 	MIPS_SYS(sys_sigreturn	, 0)
-	MIPS_SYS(sys_clone	, 0)	/* 4120 */
+	MIPS_SYS(sys_clone	, 6)	/* 4120 */
 	MIPS_SYS(sys_setdomainname, 2)
 	MIPS_SYS(sys_newuname	, 1)
 	MIPS_SYS(sys_ni_syscall	, 0)	/* sys_modify_ldt */