ncurses 6.1 - patch 20180623

ncurses 6.1 - patch 20180623

+ use _WIN32/_WIN64 in preference to __MINGW32__/__MINGW64__ symbols
  to simplify building with MSVC, since the former are defined in both
  compiler configurations (report by Ali Abdulkadir).
+ further improvements to configure-checks from work on dialog, i.e.,
  updated CF_ADD_INCDIR, CF_FIND_LINKAGE, CF_GCC_WARNINGS,
  CF_GNU_SOURCE, CF_LARGEFILE, CF_POSIX_C_SOURCE, CF_SIZECHANGE, and
  CF_TRY_XOPEN_SOURCE.
+ update config.guess, config.sub from
	http://git.savannah.gnu.org/cgit/config.git