vchoi_fork

[svn-r19174] Bug fix for #1239 - The filter's public function CAN_APPLY should return htri_t not 
herr_t.  To minimize the change of the library's behavior, in the function 
H5Z_prelude_callback of H5Z.c, if the return value of can_apply is FALSE and
the filter is MANDATE, this function returns a FAILURE.  If the return value is FALSE 
but the filter is OPTIONAL, this function returns a SUCCEED.  During the IO, the filter 
will fail and return a size of zero.  But the pipeline will skip this filter. 

Tested on jam, lnew, and amani.  Tested on jam with szip.