Fixes #55. ifdef out HDF4 readers

[mathomp4]

Note: The change seems more exciting than it is because my editor strips off trailing whitespace. To better see the change, use the "no whitespace" option: https://github.com/GEOS-ESM/GEOSldas_GridComp/pull/56/files?w=1

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Closes #55

This PR adds #if 0 blocks around code that uses the HDF4 Fortran interface. As stated in #55, HDF4 (at the moment) no longer supports a Fortran interface (due to implementation bugs in the library)

Per #55 (comment) by @gmao-rreichle, a solution is to just #if 0 the offending code so it remains, but isn't compiled (thus removing the need for HDF4).

I think this is all that's needed, and it does build with ifx but I'm a bit scared as that was a lot of code I ifdef'd. I think in the end it turns off support for:

    case ('ae_l2_sm_a', 'ae_l2_sm_d')
...
    case ('MOD10C1','MYD10C1')

and if those are still assimilated...

So, I'll keep it Draft until @biljanaorescanin can do a test.

[github-actions]

This PR is being prevented from merging because you have added one of our blocking labels: Contingent - DNA, Needs Lead Approval, Contingent -- Do Not Approve. You'll need to remove it before this PR can be merged.

[mathomp4]

Throwing in a blocking label as we need one of the obs this turns off.