+20170429
+ + corrected a case where $with_gpm was set to "maybe" after CF_WITH_GPM,
+ overlooked in 20160528 fixes (report by Alexandre Bury).
+ + improve a couple of test-program's help-messages.
+ + corrected loop in rain.c from 20170415 changes.
+ + modify winnstr and winchnstr to return error if the output pointer is
+ null, as well as adding a null pointer check of the window pointer
+ for better compatibility with other implementations.
+ + improve discussion of NetBSD curses in scr_dump.5
+ + modify LIMIT_TYPED macro in new_pair.h to avoid changing sign of the
+ value to be limited (reports by Darby Payne, Rob Boudreau).
+ + update config.guess, config.sub from
+ http://git.savannah.gnu.org/cgit/config.git
+