Fixes #3706: Move r28962 to v1.7 (PMI max name length)

From patch

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r28962 [[BR]]
Don't just hardcode the max length of the PMI name as it could be wrong. PMI2 installations seem to be retaining at least some of the PMI functions, so use the one to get the max name length.
Fixes #3646: Move OB1 improvements to Open MPI 1.7.3

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r26865 [[BR]]
Typo.

r26871 [[BR]]
Fix the MPI_Cancel issue identified by Fujitsu. And a typo.

r26956 [[BR]]
adding a fragmentation mechanism to the Get flow in function mca_pml_ob1_recv_request_progress_rget

r27018 [[BR]]
pml/ob1: fix bugs in mca_pml_ob1_recv_request_progress_rget

r28667 [[BR]]
Fix case where amount of data sent is less than expected.  Otherwise, we will get hang when running the RGET protocol.
Reviewed by hjelm,bosilca.
Fixes #3723: Move r29024 to v1.7 branch (coll/ml: fix typo in assert)

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r29024 [[BR]]
coll/ml: fix typo in assert that could cause an abort in debug builds.

cmr=v1.7.3:reviewer=manjugv