ncurses 6.1 - patch 20180317

ncurses 6.1 - patch 20180317

+ fix a check in infotocap which may not have detected a problem when
  it should have.
+ add a check in tic for the case where setf/setb are given using
  different strings, but provide identical results to setaf/setab.
+ further improve fix for terminfo.5 (patch by Kir Kolyshkin).
+ reorder loop-limit checks in winsnstr() in case the string has no
  terminating null and only the number of characters is used (patch
  by Gyorgy Jeney).