patch 8.1.0857: indent functionality is not separated

Problem:    Ignore functionality is not separated.
Solution:   Move indent functionality into a new file. (Yegappan Lakshmanan,
            closes #3886)
diff --git a/src/Make_cyg_ming.mak b/src/Make_cyg_ming.mak
index 8d8666f..5795b50 100644
--- a/src/Make_cyg_ming.mak
+++ b/src/Make_cyg_ming.mak
@@ -720,6 +720,7 @@
 	$(OUTDIR)/getchar.o \
 	$(OUTDIR)/hardcopy.o \
 	$(OUTDIR)/hashtab.o \
+	$(OUTDIR)/indent.o \
 	$(OUTDIR)/json.o \
 	$(OUTDIR)/list.o \
 	$(OUTDIR)/main.o \