Special-case objc2 less in header-translator #3222

Job	Run time
Check MSRV	56s
Check formatting	10s
Lint macOS x86_64	3m 16s
Lint iOS ARMv7s	3m 6s
Lint visionOS Aarch64 simulator	3m 8s
Lint GNUStep + exceptions	1m 26s
Lint header-translator	33s
Lint test-assembly	32s
Test macOS 15 Aarch64	1m 38s
Check framework features	0s
Assembly tests	51s
Verify header translator output	1m 50s
${{ ((matrix.test && 'Test') \|\| 'Build') }} ${{ matrix.name }}	0s
Test Compiler-RT	25s
Test GNUStep with libobjc2 v1.9	1m 7s
Compiler UI	45s
Test on iOS simulator w. dinghy	0s
Test GNUStep with libobjc2 v2.0	1m 28s
Test GNUStep with libobjc2 v2.1 on nightly	53s
Test GNUStep 32bit	1m 38s
	23m 42s

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