make: add a variable 'DOMAIN' for the name of the pot and mo files

Having the name of the domain hard-coded in many places in the makefiles
makes it harder to maintain them, specially because much code is duplicated
between the makefiles that handle po files.

There is now the variable DOMAIN that is set once in each concerned
makefile, and the rest of the makefile makes use of it.

Signed-off-by: Christophe CURIS <christophe.curis@free.fr>

WINGs/po/Makefile.am

@@ -1,8 +1,10 @@
+DOMAIN = WINGs
+
 nlsdir      = $(NLSDIR)
 
 CATALOGS = @WINGSMOFILES@
 
-CLEANFILES = $(CATALOGS) WINGs.pot
+CLEANFILES = $(CATALOGS) $(DOMAIN).pot
 
 EXTRA_DIST = bg.po ca.po cs.po de.po fr.po hu.po nl.po sk.po
 
@@ -77,13 +79,13 @@ SUFFIXES = .po .mo
 
 all-local: $(CATALOGS)
 
-WINGs.pot: $(POTFILES)
-	xgettext --default-domain=WINGs \
+$(DOMAIN).pot: $(POTFILES)
+	xgettext --default-domain=$(DOMAIN) \
 	--add-comments --keyword=_ --keyword=N_ $(POTFILES)
-	if cmp -s WINGs.po WINGs.pot; then \
-	    rm -f WINGs.po; \
+	if cmp -s $(DOMAIN).po $(DOMAIN).pot; then \
+	    rm -f $(DOMAIN).po; \
 	else \
-	    mv -f WINGs.po WINGs.pot; \
+	    mv -f $(DOMAIN).po $(DOMAIN).pot; \
 	fi
 
 install-data-local:  $(CATALOGS)
@@ -92,7 +94,7 @@ install-data-local:  $(CATALOGS)
 		if test "$$n" -a "$$n" != "__DuMmY" ; then \
 			l=`basename $$n .mo`; \
 			$(mkinstalldirs) $(DESTDIR)$(nlsdir)/$$l/LC_MESSAGES; \
-			$(INSTALL_DATA) -m 644 $$n $(DESTDIR)$(nlsdir)/$$l/LC_MESSAGES/WINGs.mo; \
+			$(INSTALL_DATA) -m 644 $$n $(DESTDIR)$(nlsdir)/$$l/LC_MESSAGES/$(DOMAIN).mo; \
 		fi; \
 	done