ncurses 5.7 - patch 20091031

+ modify use of $CC environment variable which is defined by X/Open
  as a curses feature, to ignore it if it is not a single character
  (prompted by discussion with Benjamin C W Sittler).
+ add START_TRACE in slk_init
+ fix a regression in _nc_ripoffline which made test/ncurses.c not show
  soft-keys, broken in 20090927 merging.
+ change initialization of "hidden" flag for soft-keys from true to
  false, broken in 20090704 merging (Ubuntu #464274).
+ update nsterm entries (patch by Benjamin C W Sittler, prompted by
  discussion with Fabian Groffen in GenToo #206201).
+ add test/xterm-256color.dat