hdf5_ep

[svn-r19893] Purpose:
    Bug 2089 - GMQS: h5diff segfault on a compound dataset with fixed length + 
    vlen string type order

Description:
    Merged from HDF5 trunk r19892.
    This is fix for the segfault when h5diff compares a compound dataset with 
    combination of fixed length string types and vlen string types in certain 
    orders. Optimized vlariable length string handling codes. The fix is 
    referred from h5dump handling vlen strings. 
    For testing, several compound datasets were added with various combinations.
    Previous failed cases:
     - Vlen string, Fixed length string, Vlen string, Fixed length string
     - Fixed length string, Fixed length string, Vlen string, Vlen string
     - Fixed length string, Vlen string, Fixed length string, Vlen string
     
Tested:
 jam (linux32-LE), amani (linux64-LE), heiwa (linuxppc64-BE), linew (solaris-BE)