snapshots: Register new snapshots.
auto merge of #16571 : pcwalton/rust/register-snapshots, r=pcwalton
Remove 'static analysis'

This has certain implications that are wrong.

Fixes #16299.
auto merge of #16576 : steveklabnik/rust/static_analysis_gate, r=pcwalton

This has certain implications that are wrong.

Fixes #16299.
serialize/base64: Add XML-specific encodings
serialize/base64: Make from_base64 config-aware