patch 8.2.1262: src/ex_cmds.c file is too big

Problem:    src/ex_cmds.c file is too big.
Solution:   Move help related code to src/help.c. (Yegappan Lakshmanan,
            closes #6506)
diff --git a/src/Make_cyg_ming.mak b/src/Make_cyg_ming.mak
index 157dc94..3e8bb04 100644
--- a/src/Make_cyg_ming.mak
+++ b/src/Make_cyg_ming.mak
@@ -744,6 +744,7 @@
 	$(OUTDIR)/gui_xim.o \
 	$(OUTDIR)/hardcopy.o \
 	$(OUTDIR)/hashtab.o \
+	$(OUTDIR)/help.o \
 	$(OUTDIR)/highlight.o \
 	$(OUTDIR)/if_cscope.o \
 	$(OUTDIR)/indent.o \