Preserve timestamps, thanks Parag.
https://bugzilla.redhat.com/show_bug.cgi?id=xmltoman-review#c2

diff -urp xmltoman-0.3.orig/Makefile xmltoman-0.3/Makefile
--- xmltoman-0.3.orig/Makefile	2003-10-03 15:43:17.000000000 +0200
+++ xmltoman-0.3/Makefile	2008-03-12 13:16:56.000000000 +0100
@@ -12,12 +12,12 @@ xmltoman.1: xml/xmltoman.1.xml
 xmlmantohtml.1: xml/xmlmantohtml.1.xml
 	./xmltoman $< > $@
 
-install:
-	install -D xmltoman $(DESTDIR)/$(PREFIX)/bin/xmltoman
-	install -D xmlmantohtml $(DESTDIR)/$(PREFIX)/bin/xmlmantohtml
-	install -D -m 0644 xmltoman.dtd $(DESTDIR)/$(PREFIX)/share/xmltoman/xmltoman.dtd
-	install -D -m 0644 xmltoman.css $(DESTDIR)/$(PREFIX)/share/xmltoman/xmltoman.css
-	install -D -m 0644 xmltoman.xsl $(DESTDIR)/$(PREFIX)/share/xmltoman/xmltoman.xsl
+install:
+	install -p -D xmltoman $(DESTDIR)/$(PREFIX)/bin/xmltoman
+	install -p -D xmlmantohtml $(DESTDIR)/$(PREFIX)/bin/xmlmantohtml
+	install -p -D -m 0644 xmltoman.dtd $(DESTDIR)/$(PREFIX)/share/xmltoman/xmltoman.dtd
+	install -p -D -m 0644 xmltoman.css $(DESTDIR)/$(PREFIX)/share/xmltoman/xmltoman.css
+	install -p -D -m 0644 xmltoman.xsl $(DESTDIR)/$(PREFIX)/share/xmltoman/xmltoman.xsl
 
 dist:
 	[ -d $(DISTNAME) ] && rm -rf $(DISTNAME) || true