Remove unused functions and arguments from rustc_serialize

[bjorn3]

No description provided.

[rust-highfive]

r? @varkor

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[bjorn3]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[bors]

⌛ Trying commit a2c4aff with merge ac0b59d6d4be322e6627f407ad70bef62ff5492a...

[bors]

☀️ Try build successful - checks-actions
Build commit: ac0b59d6d4be322e6627f407ad70bef62ff5492a (ac0b59d6d4be322e6627f407ad70bef62ff5492a)

[rust-timer]

Queued ac0b59d6d4be322e6627f407ad70bef62ff5492a with parent 7f9ab03, future comparison URL.

[rust-timer]

Finished benchmarking try commit (ac0b59d6d4be322e6627f407ad70bef62ff5492a): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf

[bjorn3]

Mostly improvements up to 1.5%. A few small regressions up to 0.4%.

[varkor]

@bors r+

[bors]

📌 Commit a2c4aff has been approved by varkor

[bors]

⌛ Testing commit a2c4aff with merge e4a6032...

[bors]

☀️ Test successful - checks-actions
Approved by: varkor
Pushing e4a6032 to master...