kernel: Introduce THREAD_BLOCK_TYPE_OTHER_OBJECT.

THREAD_BLOCK_TYPE_OTHER implies the "object" pointer in the
wait information is a string. But sometimes we want to pass
through objects which are not strings, for inspection in KDL.

headers/private/system/thread_defs.h

@@ -30,6 +30,7 @@ enum {
 	THREAD_BLOCK_TYPE_RW_LOCK				= 5,
 	THREAD_BLOCK_TYPE_USER					= 6,
 
+	THREAD_BLOCK_TYPE_OTHER_OBJECT			= 9998,
 	THREAD_BLOCK_TYPE_OTHER					= 9999,
 };