Disabling the aries conduit when we're working on building mpi for cray-xc

This was an oversight that was breaking the configure step for MPI because the
GASNet autoconf scripts would complain about being unable to build the aries
conduit for the 'everything' segment.  It took me awhile to debug this because
I thought that it was in the case that we were requesting aries; turns out
that the configure args printed out by the GASNet scripts include ones that
were auto-inferred, like "you must want aries enabled."



git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@21960 3a8e244f-b0f2-452b-bcba-4c88e055c3ca
Adding the release candidate nbody performance test to the nbody graph



git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@21961 3a8e244f-b0f2-452b-bcba-4c88e055c3ca