The X11 dissector generator is no longer run automatically.

To run the dissector generator, you will need perl 5.10 and the XML::Twig
module from CPAN. You will also need 'git' to retrieve the lastest protocol
descriptions.

Once you have those, you also need the XML protocol descriptions. In the
epan/dissectors directory, run the following commands:
 git clone git://anongit.freedesktop.org/xcb/proto xcbproto
 git clone git://anongit.freedesktop.org/git/mesa/mesa

Or, if you have already cloned those repositories, "git pull" each one to bring
it up to date. Please be aware that the Mesa repository is rather large; it is
slightly more than 53MB as of this writing.

Run the following:
 make x11-dissector

This will automatically run process-x11-fields.pl (for the core protocol
definitions), and then it will run process-x11-xcb.pl to process the XML
descriptions from XCB and Mesa to generate the extension dissectors.

Once this is complete, compile wireshark as usual.