ncurses 6.2 - patch 20210102

ncurses 6.2 - patch 20210102

+ update man/curs_memleaks.3x, to include <term.h> which declares
  exit_terminfo.
+ clarify man/curs_terminfo.3x, to mention why the macro setterm is
  defined in <curses.h>, and remove it from the list of prototypes
  (prompted by patch by Graeme McCutcheon).
+ amend man/curs_terminfo.3x, to note that <curses.h> is required
  for certain functions, e.g., those using chtype or attr_t for
  types, as well as mvcur (cf: 20201031).
+ use parameter-names in prototypes in curs_sp_funcs.3x, for
  consistency with other manpages.