po: add keyword `qsTr` to Makevars

po/Makevars

@@ -10,7 +10,7 @@ subdir = po
 top_builddir = ..
 
 # These options get passed to xgettext.
-XGETTEXT_OPTIONS = --directory=.. --keyword=_ --keyword=N_ --keyword=_NS --keyword=qtr --keyword=Q_ --language=C++ --keyword=vlc_ngettext:1,2 --keyword=vlc_pgettext:1c,2 --keyword=_PNS:1c,2 --add-comments=xgettext: --from-code=UTF-8
+XGETTEXT_OPTIONS = --directory=.. --keyword=_ --keyword=N_ --keyword=_NS --keyword=qtr --keyword=qsTr --keyword=Q_ --language=C++ --keyword=vlc_ngettext:1,2 --keyword=vlc_pgettext:1c,2 --keyword=_PNS:1c,2 --add-comments=xgettext: --from-code=UTF-8
 
 # 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