Swap out the flasher stubs with the legacy C stubs #876

Job	Run time
Check (x86_64-apple-darwin)	6m 28s
Check (x86_64-unknown-linux-gnu)	4m 55s
Check lib (x86_64-unknown-linux-gnu)	45s
Check (x86_64-unknown-linux-musl)	5m 6s
Check lib (aarch64-unknown-linux-gnu)	2m 45s
Check (aarch64-unknown-linux-gnu)	6m 13s
Check lib (armv7-unknown-linux-gnueabihf)	2m 12s
Check (armv7-unknown-linux-gnueabihf)	6m 7s
Check (x86_64-pc-windows-msvc)	9m 32s
Clippy	2m 46s
Check lib MSRV (x86_64-unknown-linux-gnu)	1m 8s
Rustfmt	29s
Unit Tests	1m 26s
Check lib MSRV (aarch64-unknown-linux-gnu)	2m 33s
Check lib MSRV (armv7-unknown-linux-gnueabihf)	2m 8s
	54m 33s

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