Add new tests
Description:
Collective IO doesn't work for some platforms/mpio packages when more than
one process has no contributions to IO.
Solution:
1. Add a collective IO test to verify the correctness of the library when
more than one process has no contributions to IO.
2. Add the similar MPI-IO test in t_mpi to help us maintain in more platforms.
Platforms tested:
heping, mir, copper
Misc. update: