finish ChanValue: Len and Cap.

R=r
DELTA=45  (45 added, 0 deleted, 0 changed)
OCL=33873
CL=33881
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index 1e89a45..d4936af 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -493,5 +493,7 @@
 void	chanrecv(Hchan*, void*, bool*);
 void	chanclose(Hchan*);
 bool	chanclosed(Hchan*);
+int32	chanlen(Hchan*);
+int32	chancap(Hchan*);
 
 void	ifaceE2I(struct InterfaceType*, Eface, Iface*);