Make `read_clock_khr` always available #550

Job	Run time
cargo-deny	1m 19s
Test (windows-2022)	15m 53s
Android (ubuntu-24.04, aarch64-linux-android)	8m 27s
Test (macOS-latest)	9m 6s
Compiletest (windows-2022)	3m 56s
Compiletest (ubuntu-24.04)	4m 16s
Compiletest (macOS-latest)	3m 55s
Lint	6m 42s
Test (ubuntu-24.04)	8m 18s
Difftest (windows-2022)	16m 22s
Difftest (macOS-latest)	10m 7s
Difftest (ubuntu-24.04)	8m 44s
test_success	3s
	1h 37m 8s

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