isic: Fixup makefile to support destination

Backport:
http://pkgs.fedoraproject.org/cgit/isic.git/tree/isic-0.07-make.patch

Signed-off-by: Armin Kuster <akuser808@gmail.com>

Index: isic-0.07/Makefile.in
===================================================================
--- isic-0.07.orig/Makefile.in
+++ isic-0.07/Makefile.in
@@ -63,7 +63,7 @@ package: distclean
 	  tar -czvf isic-$(VERSION).tgz ./isic-$(VERSION)/* )
 
 install: $(BINS) $(MAN)
-	$(INSTALL) -m 0755 -d $(PREFIX)/bin
-	$(INSTALL) -m 0755 -c $(BINS) $(PREFIX)/bin
-	$(INSTALL) -m 0755 -d $(PREFIX)/man/man1
-	${INSTALL} -m 0755 -c $(MAN) $(PREFIX)/man/man1
+	$(INSTALL) -m 0755 -d $(DESTDIR)$(PREFIX)/bin
+	$(INSTALL) -m 0755 -c $(BINS) $(DESTDIR)$(PREFIX)/bin
+	$(INSTALL) -m 0755 -d $(DESTDIR)$(PREFIX)/share/man/man1
+	${INSTALL} -m 0755 -c $(MAN) $(DESTDIR)$(PREFIX)/share/man/man1
