ncurses 6.1 - patch 20190928

+ amend the ncurse*-config and pc-files to take into account the rpath
  hack which differed between those files.
+ improve -L option filtering in ncurses*-config
+ improve recovery from error when reading command-character in
  test/ncurses.c, showing the relevant error message and not exiting on
  EINTR (cf: 20180922)