Revert r190105 so that removing options KDB but DDB or GDB being

available will cause the kernel to not respect -d and boot_kdb=1
for consistency with the other platforms as pointed out by marcel@.

sys/sparc64/sparc64/machdep.c

@@ -496,8 +496,10 @@ sparc64_init(caddr_t mdp, u_long o1, u_long o2, u_long o3, ofw_vec_t *vec)
 
 	kdb_init();
 
+#ifdef KDB
 	if (boothowto & RB_KDB)
 		kdb_enter(KDB_WHY_BOOTFLAGS, "Boot flags requested debugger");
+#endif
 }
 
 void