Switch to using the query/priority method for selecting
MTLs. This switch was motivated by the fact that now
on some platforms, its possible for multiple MTLs to
be initializable, but only one MTL should be selected.
In addition, there is a complication with the PSM and
IFO (with PSM provider) MTLs owing to the fact that
they cannot both intialize the underlying PSM context,
i.e. only one call to psm_init is allowed per process.
The mxm component has not been compiled as the author
doesn't currently have access to a system with a recent
enough mxm installed to allow for a compile.
The portals4, ofi, and psm components have been checked
for compilation. The ofi and psm components have been
checked for runtime correctness on a intel/qlogic system
with up to date PSM installed.
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