Make executeRpcCall only compute rpcCallData once
Make executeRpcCall only compute rpcCallData once

This is important for distMCsAsyncTask, because currently every time
config.data is updated, wconfd generates a separate copy of the Base64
encoded, zlib compressed config.data payload string for the
/upload_file_single call sent to each master candidate's noded.

This patch causes it to generate one copy of the string and send that
in parallel to all MCs.

Signed-off-by: Brian Foley <a00e555871a6a538e97f8c44307104c884f8e869@google.com>
Reviewed-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>

onponomarev/ganeti,mbakke/ganeti,yiannist/ganeti,yiannist/ganeti,ganeti/ganeti,andir/ganeti,yiannist/ganeti,ganeti/ganeti,mbakke/ganeti,onponomarev/ganeti,andir/ganeti,andir/ganeti,mbakke/ganeti,ganeti/ganeti