hdf5_ep

[svn-r4138] 
Purpose:
    Bug Fix
Description:
    In order for libtool to point to the place zlib lives (when
    specified) it needs to add that flag to the LDFLAGS macro. However,
    since we're getting this information from the top-level configure,
    it's cached. Thus, we don't check for it and the -L flag doesn't get
    included into the LDFLAGS macro.
Solution:
    Remove the cached value so that the Fortran configure will always
    check for zlib even if it's found by the top-level configure.
Platforms tested:
    Kelgia