[S390] Define GENERIC_LOCKBREAK.

Fix compile error:

  CC      arch/s390/kernel/asm-offsets.s
In file included from
arch/s390/kernel/asm-offsets.c:7:
include/linux/sched.h: In function 'spin_needbreak':
include/linux/sched.h:1931: error: implicit declaration of function '__raw_spin_is_contended'
make[2]: *** [arch/s390/kernel/asm-offsets.s] Error 1

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/Kconfig

@@ -47,6 +47,11 @@ config NO_IOMEM
 config NO_DMA
 	def_bool y
 
+config GENERIC_LOCKBREAK
+	bool
+	default y
+	depends on SMP && PREEMPT
+
 mainmenu "Linux Kernel Configuration"
 
 config S390