patch 8.1.1282: running make in src/po leaves LINGUAS file behind

Problem:    Running make in src/po leaves LINGUAS file behind. (Ken Takata)
Solution:   Delete LINGUAS after running msgfmt.
diff --git a/src/po/Makefile b/src/po/Makefile
index cc56b83..6049b49 100644
--- a/src/po/Makefile
+++ b/src/po/Makefile
@@ -168,10 +168,12 @@
 vim.desktop: vim.desktop.in $(POFILES)
 	@echo $(LANGUAGES) | tr " " "\n" |sed -e '/\./d' | sort > LINGUAS
 	$(MSGFMT) --desktop -d . --template vim.desktop.in -o vim.desktop
+	rm -f LINGUAS
 
 gvim.desktop: gvim.desktop.in $(POFILES)
 	@echo $(LANGUAGES) | tr " " "\n" |sed -e '/\./d' | sort > LINGUAS
 	$(MSGFMT) --desktop -d . --template gvim.desktop.in -o gvim.desktop
+	rm -f LINGUAS
 
 update-po: $(LANGUAGES)