Add GPL comment


sql/share/czech/errmsg.txt:
  Add GPL comment
sql/share/danish/errmsg.txt:
  Add GPL comment
sql/share/dutch/errmsg.txt:
  Add GPL comment
sql/share/english/errmsg.txt:
  Add GPL comment
sql/share/estonian/errmsg.txt:
  Add GPL comment
sql/share/french/errmsg.txt:
  Add GPL comment
sql/share/german/errmsg.txt:
  Add GPL comment
sql/share/greek/errmsg.txt:
  Add GPL comment
sql/share/hungarian/errmsg.txt:
  Add GPL comment
sql/share/italian/errmsg.txt:
  Add GPL comment
sql/share/japanese/errmsg.txt:
  Add GPL comment
sql/share/korean/errmsg.txt:
  Add GPL comment
sql/share/norwegian-ny/errmsg.txt:
  Add GPL comment
sql/share/norwegian/errmsg.txt:
  Add GPL comment
sql/share/polish/errmsg.txt:
  Add GPL comment
sql/share/portuguese/errmsg.txt:
  Add GPL comment
sql/share/romanian/errmsg.txt:
  Add GPL comment
sql/share/russian/errmsg.txt:
  Add GPL comment
sql/share/slovak/errmsg.txt:
  Add GPL comment
sql/share/spanish/errmsg.txt:
  Add GPL comment
sql/share/swedish/errmsg.txt:
  Add GPL comment
sql/share/ukrainian/errmsg.txt:
  Add GPL comment