Respect target-cpu in RUSTFLAGS #1034

Job	Run time
spellcheck	9s
Check	14s
Clippy	26s
Rustfmt	4s
Test Suite (ubuntu-latest, 1.74.0, 0.10.1)	14m 19s
Test Suite (ubuntu-latest, 1.74.0, 0.11.0)	14m 52s
Test Suite (ubuntu-latest, stable, 0.10.1)	16m 41s
Test Suite (ubuntu-latest, stable, 0.11.0)	14m 7s
Test Suite (ubuntu-latest, stable, master)	3m 5s
Test Suite (ubuntu-latest, nightly, 0.10.1)	13m 59s
Test Suite (ubuntu-latest, nightly, 0.11.0)	14m 4s
Test Suite (ubuntu-latest, nightly, master)	2m 47s
Test Suite (macos-13, 1.74.0, 0.10.1)	31m 38s
Test Suite (macos-13, 1.74.0, 0.11.0)	26m 36s
Test Suite (macos-13, stable, 0.10.1)	23m 37s
Test Suite (macos-13, stable, 0.11.0)	20m 14s
Test Suite (macos-13, stable, master)	6m 25s
Test Suite (macos-13, nightly, 0.10.1)	25m 55s
Test Suite (macos-13, nightly, 0.11.0)	21m 33s
Test Suite (macos-13, nightly, master)	7m 49s
Test Suite (windows-latest, 1.74.0, 0.10.1)	26m 19s
Test Suite (windows-latest, 1.74.0, 0.11.0)	26m 6s
Test Suite (windows-latest, stable, 0.10.1)	23m 40s
Test Suite (windows-latest, stable, 0.11.0)	24m 40s
Test Suite (windows-latest, stable, master)	8m 7s
Test Suite (windows-latest, nightly, 0.10.1)	21m 28s
Test Suite (windows-latest, nightly, 0.11.0)	23m 14s
Test Suite (windows-latest, nightly, master)	7m 17s
	6h 59m 25s

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