update sessions API to that being proposed

[hppritcha]

There were some minor changes to the sessions API starting with the 9/19 MPI Forum. These include:

• addition of an MPI_INFO argument to get_num_psets and get_nth_pset
• dropping of the get_nth_psetlen function
• modify the get_nth_pset function to have an in/out for the len arg

Signed-off-by: Howard Pritchard howardp@lanl.gov

[hppritcha]

@hjelmn take a look if you have a chance this week.