Backport build.rs fixes to 2.x. #1729

Job	Run time
Check Cross-Compilation on Rust nightly on Windows (nightly)	54s
Check Cross-Compilation (stable)	42s
Check Cross-Compilation on Windows (stable)	1m 0s
Check Cross-Compilation (beta)	48s
Check Cross-Compilation on Rust nightly (nightly)	2m 29s
Fuzz Targets	52s
Check Cross-Compilation on Windows (beta)	54s
Rustfmt	10s
Test linux-raw support (ubuntu)	29s
Test (msrv)	2m 30s
Test linux-raw support (ubuntu-20.04)	28s
Test (stable)	15s
Test on Musl (ubuntu)	34s
Test (windows-latest)	17s
Test (windows-2019)	20s
Test with Rust nightly (ubuntu)	29s
Test (macos-latest)	17s
Test with Rust nightly (windows)	43s
Test (macos-12)	33s
Test (beta)	1s
Test (ubuntu-20.04)	25s
Test (aarch64-ubuntu)	1s
	15m 11s

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