Change to https for tigervnc URL

Our main web site now supports https, so update all references.
diff --git a/vncviewer/vncviewer.cxx b/vncviewer/vncviewer.cxx
index 8d79510..ac4afca 100644
--- a/vncviewer/vncviewer.cxx
+++ b/vncviewer/vncviewer.cxx
@@ -100,7 +100,7 @@
            _("TigerVNC Viewer %d-bit v%s\n"
              "Built on: %s\n"
              "Copyright (C) 1999-%d TigerVNC Team and many others (see README.rst)\n"
-             "See http://www.tigervnc.org for information on TigerVNC."),
+             "See https://www.tigervnc.org for information on TigerVNC."),
            (int)sizeof(size_t)*8, PACKAGE_VERSION,
            BUILD_TIMESTAMP, 2018);
 
diff --git a/vncviewer/vncviewer.man b/vncviewer/vncviewer.man
index 421290f..8762dfb 100644
--- a/vncviewer/vncviewer.man
+++ b/vncviewer/vncviewer.man
@@ -320,7 +320,7 @@
 .BR vncconfig (1),
 .BR vncserver (1)
 .br
-http://www.tigervnc.org
+https://www.tigervnc.org
 
 .SH AUTHOR
 Tristan Richardson, RealVNC Ltd. and others.