Add missing alignment padding to SetupRequest struct

Fields  AuthorizationProtocolName and AuthorizationProtocolData of
SetupRequest should be padded:

http://www.x.org/releases/current/doc/xproto/x11protocol.html#Encoding::Connection_Setup

The problem was discovered by github user pphaneuf while trying to use xgb
to write his own implementation of the connection handshake. Neither xgb
nor xcb actually use code generated for SetupRequest for the handshake,
which is why this bug went unnoticed.

BurntSushi/xgb#24

Alessandro Arzilli.

Reviewed-by: Christian Linhart <chris@demorecorder.com>

src/xproto.xml

@@ -198,9 +198,11 @@ authorization from the authors.
     <list type="char" name="authorization_protocol_name">
       <fieldref>authorization_protocol_name_len</fieldref>
     </list>
+    <pad align="4" />
     <list type="char" name="authorization_protocol_data">
       <fieldref>authorization_protocol_data_len</fieldref>
     </list>
+    <pad align="4" />
   </struct>
 
   <struct name="SetupFailed">