[Feature Request] Interface for determining if HDF5 was built with support for parallel enabled

[jhendersonHDF]

A user made a feature request to add an interface that would return whether HDF5 was built with parallel/MPI support, similar to H5is_library_threadsafe. Applications can currently check this through the use of #ifdef H5_HAVE_PARALLEL, though there may be some use in having an API routine that returns this information.

[simonbyrne]

This would be very helpful for the Julia bindings (HDF5.jl) as we have no way of querying the header macros (we call directly into the library).