Increase version string buffer size for gcc

There is some bug in gcc's new -Werror=format-overflow that makes it
think majorVersion could end up being very large. Increase the target
buffer for now to keep gcc happy.

common/rfb/CConnection.cxx

@@ -143,7 +143,7 @@ void CConnection::processMsg()
 
 void CConnection::processVersionMsg()
 {
-  char verStr[13];
+  char verStr[27]; // FIXME: gcc has some bug in format-overflow
   int majorVersion;
   int minorVersion;