po: switch to using LINGUAS file for list of languages

To enable translation management systems to add new languages they need
to be able to modify the supported language list. The LINGUAS file is a
simple standard format that can be used for the language list, as this
is easier than modifying make variables.
Reviewed-by: NPavel Hrdina <phrdina@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

po/LINGUAS

+af
+am
+anp
+ar
+as
+ast
+bal
+be
+bg
+bn_IN
+bn
+bo
+br
+brx
+bs
+ca
+cs
+cy
+da
+de_CH
+de
+el
+en_GB
+eo
+es
+et
+eu
+fa
+fil
+fi
+fr
+fur
+ga
+gl
+gu
+he
+hi
+hr
+hu
+ia
+id
+ilo
+is
+it
+ja
+ka
+kk
+km
+kn
+ko
+kw_GB
+kw@kkcor
+kw
+kw@uccor
+ky
+lt
+lv
+mai
+mk
+ml
+mn
+mr
+ms
+my
+nb
+nds
+ne
+nl
+nn
+nso
+or
+pa
+pl
+pt_BR
+pt
+ro
+ru
+si
+sk
+sl
+sq
+sr@latin
+sr
+sv
+ta
+te
+tg
+th
+tr
+tw
+uk
+ur
+vi
+wba
+yo
+zh_CN
+zh_HK
+zh_TW
+zu

po/Makefile.am

@@ -2,18 +2,7 @@ DOMAIN = $(PACKAGE_NAME)
 COPYRIGHT_HOLDER = The Libvirt authors
 MSGID_BUGS_ADDRESS = https://libvirt.org/bugs.html
 
-LANGS := \
-	af am anp ar as ast bal be bg bn_IN \
-	bn bo br brx bs ca cs cy da de_CH \
-	de el en_GB eo es et eu fa fil fi \
-	fr fur ga gl gu he hi hr hu ia \
-	id ilo is it ja ka kk km kn ko \
-	kw_GB kw@kkcor kw kw@uccor ky lt lv mai mk ml \
-	mn mr ms my nb nds ne nl nn nso \
-	or pa pl pt_BR pt ro ru si sk sl \
-	sq sr@latin sr sv ta te tg th tr tw \
-	uk ur vi wba yo zh_CN zh_HK zh_TW zu
-
+LANGS := $(shell cat $(srcdir)/LINGUAS)
 
 POTFILES_IN = $(srcdir)/POTFILES.in
 POTFILES: $(POTFILES_IN)
@@ -29,6 +18,7 @@ GMOFILES := $(LANGS:%=%.gmo)
 CLEANFILES = $(POTFILE) $(POFILES) $(GMOFILES) POTFILES
 
 EXTRA_DIST = \
+	LINGUAS \
 	$(POTFILES_IN) \
 	$(POMINIFILES)