Improve checking of invalid symbol versions

[parth-07]

This commit improves checking of invalid symbol versions. In particular, we now report errors when:

• A defined symbol contains an unknown version.
• An undefined symbol contains a version. Please note that there is no valid case where an undefined symbol can have a symbol version.

Resolves #1094

[quic-areg]

The error message undefined symbol 'foo@VER' cannot have version repeats the version since the name already contains @VER. I think these error messages are better:

lld: undefined symbol: foo@VER; gold: symbol foo has undefined version VER

[parth-07]

The error message undefined symbol 'foo@VER' cannot have version repeats the version since the name already contains @VER. I think these error messages are better:

lld: undefined symbol: foo@VER; gold: symbol foo has undefined version VER

Thank you for the suggestion. You mean the other diagnostic, %0: symbol %1 has undefined version %2, right?
The undefined symbol 'foo@VER' cannot have version was not repeating the version name. Though I was incorrectly passing the redundant version name with the config.raise() which was getting ignored.

I have modified the %0: symbol foo@UNKNOWN_VERSION has undefined version UNKNOWN_VERSION diagnostic to %0: symbol foo has undefined version UNKNOWN_VERSION.