ncurses 6.1 - patch 20190330

ncurses 6.1 - patch 20190330

+ add "screen5", to mention italics (report by Stefan Assmann)
+ modify description of xterm+x11hilite to eliminate unused p5 -TD
+ add configure script checks to help with a port to Ultrix 3.1
  (report by Dennis Grevenstein).
  + check if "b" binary feature of fopen works
  + check for missing feature of locale.h
  + add fallback for strstr() in test-programs
  + add fallback for STDOUT_FILENO in test-programs
+ update config.guess, config.sub