thorium: set mpi1_pt2pt_nonblocking as default transport subsystem
thorium: set mpi1_pt2pt_nonblocking as default transport subsystem

the memory leak reported in #783 is no longer reproducible.

Link: https://github.com/GeneAssembly/biosal/issues/782
Link: https://github.com/GeneAssembly/biosal/issues/783
Signed-off-by: Sébastien Boisvert <1a4d2e25eb5ba040b6ad5779a730a1a8a0ff9bc5@anl.gov>

GeneAssembly/biosal,GeneAssembly/biosal,sebhtml/biosal,sebhtml/biosal,GeneAssembly/biosal,GeneAssembly/biosal,sebhtml/biosal,sebhtml/biosal,GeneAssembly/biosal,sebhtml/biosal,sebhtml/biosal,GeneAssembly/biosal