Backport build.rs fixes to 2.x. #1730

Job	Run time
Check Cross-Compilation (stable)	30s
Check Cross-Compilation on Rust nightly (nightly)	2m 4s
Check Cross-Compilation on Windows (stable)	2m 15s
Check Cross-Compilation (beta)	1m 9s
Check Cross-Compilation on Rust nightly on Windows (nightly)	49s
Check Cross-Compilation on Windows (beta)	1m 39s
Rustfmt	5s
Test (stable)	25s
Test linux-raw support (ubuntu)	28s
Test on Musl (ubuntu)	38s
Test (windows-latest)	2m 13s
Test linux-raw support (ubuntu-20.04)	30s
Test (windows-2019)	2m 22s
Test (macos-latest)	30s
Test with Rust nightly (ubuntu)	29s
Test (macos-12)	57s
Fuzz Targets	42s
Test with Rust nightly (windows)	37s
Test (msrv)	2m 19s
Test (beta)	32s
Test (ubuntu-20.04)	30s
Test (aarch64-ubuntu)	2m 45s
	24m 28s

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