hdf5_der

[svn-r19062] Fix coverity item 450.  Check to see if chk_proxy has been allocated before
attempting to free it.

Fix coverity item 454.  Check to see if allocation of buf failed in
H5D_fill_refill_vl.

Fix coverity items 455-457.  Initilize hid_t's to -1, check their value before
attempting to close them, and check if the close failed.

Tested: Fedora