Backport build.rs fixes to 2.x. #1733

Job	Run time
Check Cross-Compilation on Windows (stable)	2m 47s
Check Cross-Compilation on Windows (beta)	1m 30s
Check Cross-Compilation on Rust nightly (nightly)	1m 58s
Check Cross-Compilation on Rust nightly on Windows (nightly)	1m 31s
Check Cross-Compilation (stable)	1m 19s
Check Cross-Compilation (beta)	1m 29s
Fuzz Targets	43s
Rustfmt	6s
Test (stable)	42s
Test (windows-latest)	2m 14s
Test linux-raw support (ubuntu)	30s
Test (msrv)	2m 19s
Test (windows-2019)	2m 35s
Test linux-raw support (ubuntu-20.04)	30s
Test on Musl (ubuntu)	49s
Test (macos-latest)	29s
Test (macos-12)	46s
Test with Rust nightly (ubuntu)	30s
Test (beta)	32s
Test with Rust nightly (windows)	1m 28s
Test (ubuntu-20.04)	28s
Test (aarch64-ubuntu)	2m 29s
	27m 44s

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