Translations: Use the xgettext option --add-location=file

(cherry picked from commit 093490b58271e9424ce38a7b1b38bcf61b9c86c6)

po/Makevars

@@ -14,7 +14,8 @@ subdir = po
 top_builddir = ..
 
 # These options get passed to xgettext.
-XGETTEXT_OPTIONS = --keyword=_ --keyword=N_ --no-wrap --package-name='XZ Utils'
+XGETTEXT_OPTIONS = --keyword=_ --keyword=N_ \
+	--add-location=file --no-wrap --package-name='XZ Utils'
 
 # This is the copyright holder that gets inserted into the header of the
 # $(DOMAIN).pot file.  Set this to the copyright holder of the surrounding