ncurses 6.2 - patch 20210508

ncurses 6.2 - patch 20210508

+ modify tputs' error check to allow it to be used without first
  calling tgetent or setupterm, noting that terminfo initialization
  is requires for supporting the terminfo delay feature (report by
  Sebastiano Vigna).
+ fix several warnings from clang --analyze
+ add null-pointer check in comp_parse.c, when a "use=" clause refers
  to a nonexisting terminal description (report/patch by Miroslav
  Lichvar, cf: 20210227).