hdf5_ep

[svn-r8705] Purpose:  Bug fix and new test.

Description:  This is an enhancement after a user reported data writing failure
for array datatype of compound type with variable-length type in the v1.6 branch.

Solution:  Added new test and ran with Purify.  Fixed memory errors and leaks in
H5Tconv.c.

Platforms tested:  h5committest