hdf5_ep

[svn-r3403] Purpose:
    Fix
Description:
    On machines which use the bin/install-sh script, it wasn't picking up
    the install-sh script unless it was one directory depth away from it
    (ie, it thought that it was in ../bin/install-sh, which isn't good
    if, like with the documentation, it's in a deeper directory).
Solution:
    Hacked it up so that, if it does use the broken relative-path schema,
    then it will change it to use the $(top_srcdir) macro instead.
Platforms tested:
    Linux