[tlbuild] Avoid compiler warning

[Ken Brown]

This is minor, but there is a gcc warning (or error) if dvidvi is built 
with -Wformat-security (or -Werror=format-security).  The following 
patch fixes it.

--- Build/source/texk/dvidvi/dvidvi.c   (revision 47453)
+++ Build/source/texk/dvidvi/dvidvi.c   (working copy)
@@ -138,7 +138,7 @@
  char *iname ;                 /* input dvi file name */
  char *strings ;               /* pointer of the string pool */

-char banner[] = BANNER ;      /* the startup message */
+const char banner[] = BANNER ;      /* the startup message */
  integer inlength ;      /* the length of the input dvi file */
  integer postloc ;       /* location of the postamble */
  integer mag ;           /* magnification factor */


Ken