Implement QueryExports in luxid

...by handling as a classical query, using that queries for
export are already implemented. Note that QueryExport is slightly
different from other Query* Luxi requests, in that the fields are
not passed with the request, but have a fixed value.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>

src/Ganeti/Query/Server.hs

@@ -221,6 +221,10 @@ handleCall _ _ cfg (QueryConfigValues fields) = do
   answerEval <- sequence answer
   return . Ok . showJSON $ answerEval
 
+handleCall _ _ cfg (QueryExports nodes lock) =
+  handleClassicQuery cfg (Qlang.ItemTypeOpCode Qlang.QRExport)
+    (map Left nodes) ["node", "export"] lock
+
 handleCall qlock qstat cfg (SubmitJobToDrainedQueue ops) = runResultT $ do
     let mcs = Config.getMasterCandidates cfg
     jid <- mkResultT $ allocateJobId mcs qlock