patch 8.2.0557: no IPv6 support for channels

Problem:    No IPv6 support for channels.
Solution:   Add IPv6 support. (Ozaki Kiichi, closes #5893)
diff --git a/src/Make_cyg_ming.mak b/src/Make_cyg_ming.mak
index 8698648..091102e 100644
--- a/src/Make_cyg_ming.mak
+++ b/src/Make_cyg_ming.mak
@@ -850,7 +850,7 @@
 
 ifeq ($(CHANNEL),yes)
 OBJ += $(OUTDIR)/channel.o
-LIB += -lwsock32
+LIB += -lwsock32 -lws2_32
 endif
 
 ifeq ($(DIRECTX),yes)