hdf5_ep

[svn-r16451] Repaired intermittant failure of the t_cache test in testpar.

The failure was caused by some over active sanity checking code in 
unlock_entry().  In essence the code did not consider the possibility
that under certain, very unusual circumstances, an entry could be flushed
to disk during the H5AC_unprotect() call.  Instead, it simply failed
if a dirty entry was marked clean after the call to H5AC_unprotect().

This bug in the test code was exposed by recent changes to the default
cache configuration made as part of the "metadata blizard" bug fix.

Fixed the bug by adding code to detect when an entry is flushed during 
the call to H5AC_unprotect(), and not trigger a failure if a dirty entry
is marked clean after a call to H5AC_unprotect() if the entry has been
flushed.

In passing also found and fixed another test bug in which expunged 
entries were erroneously marked as dirty in the test code's independant
register of entry status.


Tested parallel on Phoenix (AMD64 Linux) and Jam.  Also ran t_cache
manually hundreds of times looking for intermittant failures.

Larry kindly tested (parallel) on Mercury.