Rust

Merge pull request #387 from mstange/symbol-download-improvements #1289

Job	Run time
format	9s
windows aarch64 (aarch64-pc-windows-msvc)	3m 33s
cross (aarch64-unknown-linux-gnu)	3m 44s
build & test (x86_64-unknown-linux-gnu)	2m 27s
cross (aarch64-linux-android)	4m 13s
build & test (x86_64-unknown-linux-musl)	2m 30s
build & test (aarch64-apple-darwin)	2m 33s
build & test (x86_64-apple-darwin)	1m 50s
build & test (x86_64-pc-windows-msvc)	5m 11s
	26m 10s

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