t/verify: detect OS properly #784

Job	Run time
build (linux-gcc)	2m 27s
build (linux-clang)	2m 44s
build-containers (debian, debian, bookworm, x86_64)	1m 31s
build (macos)	2m 34s
build-containers (fedora, fedora, 40, x86_64)	2m 13s
build (linux-i686-gcc)	1m 25s
build-containers (alma, almalinux, 9, x86_64)	2m 36s
build-containers (oracle, oraclelinux, 9, x86_64)	2m 28s
build (android)	38s
build (windows-cygwin-64)	5m 1s
build-containers (rocky, rockylinux, 9, x86_64)	2m 37s
build (windows-cygwin-32)	4m 40s
build-containers (ubuntu, ubuntu, noble, i686)	1m 19s
build (windows-msys2-64)	3m 21s
build-containers (ubuntu, ubuntu, noble, x86_64)	2m 44s
build (android-recovery, ubuntu-22.04, aarch64-linux-android32)	41s
	38m 59s

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