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_manx.mak b/src/Make_manx.mak
index b71b923..a44ad65 100644
--- a/src/Make_manx.mak
+++ b/src/Make_manx.mak
@@ -60,6 +60,7 @@
 	getchar.c \
 	hardcopy.c \
 	hashtab.c \
+	indent.c \
 	json.c \
 	list.c \
 	main.c \
@@ -120,6 +121,7 @@
 	obj/getchar.o \
 	obj/hardcopy.o \
 	obj/hashtab.o \
+	obj/indent.o \
 	obj/json.o \
 	obj/list.o \
 	obj/main.o \
@@ -178,6 +180,7 @@
 	proto/getchar.pro \
 	proto/hardcopy.pro \
 	proto/hashtab.pro \
+	proto/indent.pro \
 	proto/json.pro \
 	proto/list.pro \
 	proto/main.pro \
@@ -329,6 +332,9 @@
 obj/hashtab.o:	hashtab.c
 	$(CCSYM) $@ hashtab.c
 
+obj/indent.o:	indent.c
+	$(CCSYM) $@ indent.c
+
 obj/json.o:	json.c
 	$(CCSYM) $@ json.c