[ticket/12744] Fix additional height of one line in header in rtl languages

PHPBB3-12744
Merge remote-tracking branch 'marc1706/ticket/12744' into develop-ascraeus

* marc1706/ticket/12744:
  [ticket/12744] Fix additional height of one line in header in rtl languages
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/12744] Fix additional height of one line in header in rtl languages