The symbol string table does not have deduplication.
Here we add code to deduplicate the symbol string table.
This has a rather large size impact (20-30%) on unstripped binaries
(typically debug binaries) but no size impact on stripped
binaries(typically release binaries).
We enable deduplication by default and add a flag to disable it
(`-no-deduplicate-symbol-strings`).
c676104875