Derive `Debug` and eq. comparison traits for `InvalidRustTarget` enum #2704

Job	Run time
minimal	19s
check-cfg	23s
docs	18s
msrv	49s
quickchecking	13s
rustfmt-clippy	25s
test (ubuntu-latest, 9.0, 0, 0, 0, 0)	1m 38s
test-book	11s
test (ubuntu-latest, 9.0, 0, 0, 1, 0)	1m 48s
test-expectations (ubuntu-latest)	37s
test-no-headers	24s
test-expectations (macos-latest)	41s
test (ubuntu-latest, 9.0, 0, 1, 0, 0)	1m 40s
test (ubuntu-latest, 9.0, 0, 1, 1, 0)	1m 39s
test (ubuntu-latest, 9.0, 1, 0, 0, 0)	2m 12s
test (ubuntu-latest, 9.0, 1, 0, 1, 0)	2m 5s
test (ubuntu-latest, 9.0, 1, 1, 0, 0)	2m 4s
test (ubuntu-latest, 9.0, 1, 1, 1, 0)	2m 7s
test (ubuntu-latest, 16.0, 0, 0, 0, 0)	4m 31s
test (ubuntu-latest, 16.0, 0, 0, 1, 0)	4m 51s
test (ubuntu-latest, 16.0, 0, 1, 0, 0)	4m 32s
test (ubuntu-latest, 16.0, 0, 1, 1, 0)	4m 31s
test (ubuntu-latest, 16.0, 1, 0, 0, 0)	8m 4s
test (ubuntu-latest, 16.0, 1, 0, 1, 0)	6m 51s
test (ubuntu-latest, 16.0, 1, 1, 0, 0)	7m 10s
test (ubuntu-latest, 16.0, 1, 1, 1, 0)	6m 36s
test (ubuntu-latest, 16.0, 0, 0, 1)	2m 24s
test (macos-latest, 16.0, 0, 0, 0)	2m 1s
success	1s
	1h 11m 5s

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