Rollup of 8 pull requests

[jackh726]

Successful merges:

• Stabilize extended_key_value_attributes #83366 (Stabilize extended_key_value_attributes)
• Fix v0 symbol mangling bug #83767 (Fix v0 symbol mangling bug)
• compiletest: "fix" FileCheck with --allow-unused-prefixes #84883 (compiletest: "fix" FileCheck with --allow-unused-prefixes)
• Only pass --[no-]gc-sections if linker is GNU ld. #85274 (Only pass --[no-]gc-sections if linker is GNU ld.)
• bootstrap: build cargo only if requested in tools #85297 (bootstrap: build cargo only if requested in tools)
• rustdoc: restore header sizes #85396 (rustdoc: restore header sizes)
• Fix must_use on Option::is_none #85425 (Fix must_use on Option::is_none)
• Fix escape handling #85438 (Fix escape handling)

Failed merges:

r? @ghost
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