[svn-r5690] Purpose:

    Bug Fix

Description:
    When parallel I/O is used, the MPI-I/O VFL driver uses a "lazy" model to
    call MPI_File_set_view() in order to reduce the number of calls to this
    function.  However, this is unsafe, because if a collective I/O which uses
    MPI derived types (and thus uses MPI_File_set_view()) is immediately
    followed by an independent I/O, the code will attempt to call
    MPI_File_set_view() in order to switch back to the default view of the
    file.  MPI_File_set_view() is a collective call however, and this causes
    the application to hang.

Solution:
    Removed "lazy" MPI_File_set_view() code, instead set the file view when it
    is needed (with MPI derived types) and immediately set the file view back to
    the default view before leaving the I/O routine.

Platforms tested:
    IRIX64 6.5 (modi4) w/parallel.  Also, tested with the latest development
    and release code for the SAF library, which now works correctly with this
    change.  (Although the release branch of the SAF library seems to have a
    bug, this 1.4.4 release candidate code gets as far as the version the SAF
    library is released on top of (1.4.2-patch1, I believe)).

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