sparc: Add kgdb support.

Current limitations:

1) On SMP single stepping has some fundamental issues,
   shared with other sw single-step architectures such
   as mips and arm.

2) On 32-bit sparc we don't support SMP kgdb yet.  That
   requires some reworking of the IPI mechanisms and
   infrastructure on that platform.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/kernel/Makefile b/arch/sparc/kernel/Makefile
index 59700aa..6e03a2a 100644
--- a/arch/sparc/kernel/Makefile
+++ b/arch/sparc/kernel/Makefile
@@ -25,3 +25,4 @@
 obj-$(CONFIG_SUN_PM) += apc.o pmc.o
 obj-$(CONFIG_MODULES) += module.o sparc_ksyms.o
 obj-$(CONFIG_SPARC_LED) += led.o
+obj-$(CONFIG_KGDB) += kgdb.o