ncurses 6.0 - patch 20170422

ncurses 6.0 - patch 20170422

+ build-fix for termcap-configuration (report by Chi-Hsuan Yen).
+ improve terminfo manual page discussion of control- and graphics-
  characters.
+ remove tic warning about "^?" in string capabilities, which was
  marked as an extension (cf: 20000610, 20110820); however all Unix
  implementations support this and X/Open Curses does not address it.
  On the other hand, termcap never did support this feature.
+ correct missing comma-separator between string capabilities in
  icl6402 and m2-nam -TD
+ restore rmir/smir in ansi+idc to better match original ansiterm+idc,
  add alias ansiterm (report by Robert King).
+ amend an old check for ambiguous use of "ma" in terminfo versus
  a termcap use, if the capability is cancelled to treat it as number.
+ correct a case in _nc_captoinfo() which read "%%" and emitted "%".
+ modify sscanf calls in _nc_infotocap() for patterns "%{number}%+%c"
  and "%'char'%+%c" to check that the final character is really 'c',
  avoiding a case in icl6404 which cannot be converted to termcap.
+ in _nc_infotocap(), add a check to ensure that terminfo "^?" is not
  written to termcap, because the BSDs did not implement that.
+ in _nc_tic_expand() and _nc_infotocap(), improve string-length check
  when deciding whether to use "^X" or "\xxx" format for control
  characters, to make the output of tic/infocmp more predictable.
+ limit termcap "%d" width to 2 digits on input, and use "%2" in
  preference to "%02" on output.
+ correct terminfo/termcap conversion of "%02" and "%03" into "%2" and
  "%3"; the result repeated the last character.
+ add man/scr_dump.5 to document screen-dump format.