gpfdist and gpcloud were shifted to top level by below commits, should
be moved out of gpAux/Makefile.

    commit 6125ac85cae720f484d0d45042131f4b859779d2
    Author: Marbin Tan <mtan@pivotal.io>
    Date:   Fri Feb 5 11:23:06 2016 -0800

        Move gpfdist to gpdb core.

    commit 4e34d8bb
    Author: Adam Lee <ali@pivotal.io>
    Date:   Wed May 24 16:53:15 2017 +0800

        Add a build flag for gpcloud