[S390] implement is_compat_task

Implement is_compat_task and use it all over the place.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 833e836..220a152 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -19,6 +19,7 @@
 #include <linux/ptrace.h>
 #include <linux/mman.h>
 #include <linux/mm.h>
+#include <linux/compat.h>
 #include <linux/smp.h>
 #include <linux/kdebug.h>
 #include <linux/smp_lock.h>
@@ -239,7 +240,7 @@
 	up_read(&mm->mmap_sem);
 	clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
 #ifdef CONFIG_COMPAT
-	compat = test_tsk_thread_flag(current, TIF_31BIT);
+	compat = is_compat_task();
 	if (compat && instruction == 0x0a77)
 		sys32_sigreturn();
 	else if (compat && instruction == 0x0aad)