read: don't use rnglists and loclists header

[philipc]

These headers don't give information that is required for parsing
range lists or location lists, because the encoding of these lists
must match the encoding of the compilation unit.

Additionally, while the standard seems to indicate that each section
has only one of these headers, in practice this is not true.
Furthermore, when there are multiple headers, they do not have to
each have the same encoding, so our parsing was wrong in this case
because we only used the encoding from the first header.

[coveralls]

Coverage decreased (-0.07%) to 87.185% when pulling 1f473fd on philipc:ranges into 6e16ab6 on gimli-rs:master.

[philipc]

Also use one RangeListTable per unit when writing, since units can have different encodings, and so the range list tables must too.