vchoi_fork

[svn-r12462] Committed a variety of metadata cache related changes:

1) Added trace file support to the metadata cache.  This allows capture
   of all metadata cache calls in trace files for purposes of optimization
   and debuging.

2) Added an expunge entry function.  This allows an entry to be deleteded
   from the cache without writing it to disk even if it is dirty.

3) Added a function call to resize pinned entries.

4) Added code to deal with entries that are dirty on load.  This is
   needed in support of a bug fix which can alter object headers on
   load to repair files.

5) Added progress reporting code to the "MDC API smoke check" test in
   cache_api.c.  To enable the progress reporting, set report_progress
   to TRUE in mdc_api_call_smoke_check().

Tested with h5committest, and a parallel test on phoenix (dual athelon
linux box).