don't show display warning in display_info initialization (bug #56651) * cdisplay.c (octave_get_display_info): Only set dpy_avail to 1 if a screen is available. * display.h, display.cc (display_info::initialize): Set m_msg instead of displaying warning. * display.h (display_info::m_msg): New data member. (display_info::message): New function.

--- a/libinterp/corefcn/display.cc	Fri Mar 22 15:42:44 2019 -0400
+++ b/libinterp/corefcn/display.cc	Sun Jul 21 10:16:11 2019 -0400
@@ -47,7 +47,7 @@
     m_dpy_avail = avail;
 
     if (msg)
-      warning ("%s", msg);
+      m_msg = msg;
   }
 }