vnc: Add break statement

This was not a bug, but it is not common practice to omit the break statement
from the last case statement before an empty default case.

Any change of the default case would introduce a bug.

This was reported as a warning by splint.
Signed-off-by: NStefan Weil <sw@weilnetz.de>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

ui/vnc-enc-hextile-template.h

@@ -175,6 +175,7 @@ static void CONCAT(send_hextile_tile_, NAME)(VncState *vs,
 	    /* we really don't have to invalidate either the bg or fg
 	       but we've lost the old values.  oh well. */
 	}
+        break;
     default:
 	break;
     }