vchoi_fork

[svn-r232] Problem: Parallel H5Fcreate failed if file doesnot exist.  When the
file does not exist, the code tried to open the file with EXCL CREATE.
ROMIO cannot handle file-open with EXCL Create due to racing problem.
The first process creates the file which then fails all
other processes.

Solution: In the parallel code, turn on TRUNC mode to allow "late" open
calls to succeed too.  It is safe to force TRUNC mode since the file is
known non-existing at that point.  The MPIO implementation has to
provide the real solution.

Platform tested: O2K with ROMIO.