ncurses 6.0 - patch 20170826

ncurses 6.0 - patch 20170826

+ fixes for "iterm2" (report by Leonardo Brondani Schenkel) -TD
+ corrected a warning from tic about keys which are the same, to skip
  over missing/cancelled values.
+ add check in tic for unnecessary use of "2" to denote a shifted
  special key.
+ improve checks in trim_sgr0, comp_parse.c and parse_entry.c, for
  cancelled string capabilities.
+ add check in _nc_parse_entry() for invalid entry name, setting the
  name to "invalid" to avoid problems storing entries.
+ add/improve checks in tic's parser to address invalid input
  + add a check in comp_scan.c to handle the special case where a
    nontext file ending with a NUL rather than newline is given to tic
    as input (Redhat #1484274).
  + allow for cancelled capabilities in _nc_save_str (Redhat #1484276).
  + add validity checks for "use=" target in _nc_parse_entry (Redhat
    #1484284).
  + check for invalid strings in postprocess_termcap (Redhat #1484285)
  + reset secondary pointers on EOF in next_char() (Redhat #1484287).
  + guard _nc_safe_strcpy() and _nc_safe_strcat() against calls using
    cancelled strings (Redhat #1484291).
+ correct typo in curs_memleaks.3x (Sven Joachim).
+ improve test/configure checks for some curses variants not based on
  X/Open Curses.
+ add options for test/configure to disable checks for form, menu and
  panel libraries.