defer po and pot file updating until package build time

This allows make to be run without polluting the tree with lots of po file
changes.

Makefile.PL

@@ -37,7 +37,7 @@ extra_build: ikiwiki.out
 	./mdwn2man ikiwiki-makerepo 1 doc/ikiwiki-makerepo.mdwn > ikiwiki-makerepo.man
 	./mdwn2man ikiwiki-transition 1 doc/ikiwiki-transition.mdwn > ikiwiki-transition.man
 	./mdwn2man ikiwiki-update-wikilist 1 doc/ikiwiki-update-wikilist.mdwn > ikiwiki-update-wikilist.man
-	$(MAKE) -C po
+	$(MAKE) -C po mo
 
 extra_clean:
 	rm -rf html doc/.ikiwiki

debian/rules

@@ -4,6 +4,7 @@ build: build-stamp
 build-stamp:
 	dh_testdir
 	perl Makefile.PL PREFIX=/usr INSTALLDIRS=vendor
+	$(MAKE) -C po
 	$(MAKE)
 	$(MAKE) test
 	touch build-stamp

po/Makefile

@@ -5,7 +5,9 @@ POTFILES=$(sort $(shell find ../IkiWiki -type f -name \*.pm)) \
 POFILES=$(wildcard *.po)
 MOFILES=$(POFILES:.po=.mo)
 
-all: ikiwiki.pot $(MOFILES)
+all: ikiwiki.pot mo
+
+mo: $(MOFILES)
 
 install: all
 	for file in $(MOFILES); do \
@@ -26,7 +28,7 @@ clean:
 %.mo: %.po
 	msgfmt -o $@ $<
 
-%.po: ikiwiki.pot
+%.po:
 	@echo -n "Merging ikiwiki.pot and $@"
 	@msgmerge $@ ikiwiki.pot -o $@.new 2>&1
 # Typically all that changes was a date or line number. I'd prefer not to