Comment (by Roland Haas):

Additional fixes as git hash b5451d1 "HDF5: add support for different sorts of h5cc" of ExternalLibraries-HDF5 since h5cc provided on macOS is different from that on Linux and accepts different options.

Still does not fix issues on homebrew where the pkg-config entry is not just missing information but returns incorrect library names -lz -llibname-NOTFOUND -llibname-NOTFOUND

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2838/supplement-pkg-config-information-by-h5cc