ncurses 6.0 - patch 20171125

ncurses 6.0 - patch 20171125

+ modify MKlib_gen.sh to avoid tracing result from getstr/getnstr
  before initialized.
+ add "-a" aspect-ratio option to picsmap.
+ add configure check for default path of rgb.txt, used in picsmap.
+ modify _nc_write_entry() to truncate too-long filename (report by
  Hosein Askari, Debian #882620).
+ build-fix for ncurses-examples with NetBSD curses:
  + it lacks the use_env() function.
  + it lacks libpanel; a recent change used the wrong ifdef symbol.
+ add a macro for is_linetouched() and adjust the function's return
  value to make it possible for most applications to check for an
  error-return (report by Midolikawa H).
+ additional manpage cleanup.
+ update config.guess, config.sub from
	http://git.savannah.gnu.org/cgit/config.git