vchoi_fork

[svn-r25954] HDFFV-9046: reorganize hdf5/perform, step 2

Last changes had caused problems with Windows platform:
1. H5private.h in io_timer.h is not accessible in the distributed shared library of tools.
   Need to move it to io_timer.c.
2. debug_start_stop_time() would not be available outside of h5perf. Some favor of compiler
   does not like it.  Screened it out for now.
3. mere "extern" is not good enough for Windows shared library. Must mark them as DLL. Need to mark them as 
   "H5TOOLS_DLL".
4. STANDALONE mode is broken. Screened out the code for now.

Tested; h5committest.