Emit compile error for unsupported OS #86

Job	Run time
Internals Bench (ubuntu-latest)	15s
Clippy (ubuntu-latest)	18s
Examples Bench (ubuntu-latest)	2m 25s
Examples Test (ubuntu-latest, stable)	35s
Internals Bench (macos-latest)	35s
Clippy (macos-latest)	1m 4s
Examples Bench (macos-latest)	4m 15s
Examples Test (ubuntu-latest, nightly)	36s
Internals Bench (windows-latest)	1m 12s
Clippy (windows-latest)	1m 39s
Examples Bench (windows-latest)	4m 20s
Examples Test (macos-latest, stable)	1m 15s
Rustdoc	5s
Examples Test (macos-latest, nightly)	2m 21s
Rustfmt	4s
Examples Test (windows-latest, stable)	1m 52s
Unit Test (ubuntu-latest, stable)	23s
Examples Test (windows-latest, nightly)	59s
Unit Test (Miri)	59s
Unit Test (ubuntu-latest, nightly)	32s
Unit Test (macos-latest, stable)	1m 17s
Unit Test (macos-latest, nightly)	46s
Unit Test (windows-latest, stable)	1m 15s
Unit Test (windows-latest, nightly)	44s
	29m 46s

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