tests: procfs: allow some mounts to fail #585

Job	Run time
cargo check (stable)	23s
cargo check (x86_64-unknown-linux-musl)	37s
cargo check (aarch64-unknown-linux-musl)	30s
cargo check (msrv)	1m 57s
cargo check (arm-unknown-linux-gnueabi)	39s
codespell	6s
clippy	42s
cargo check (arm-unknown-linux-gnueabihf)	44s
smoke-test examples	21s
cargo check (armv7-unknown-linux-gnueabihf)	41s
rustfmt	14s
cargo check (i686-unknown-linux-gnu)	37s
cargo doc	38s
cargo check (loongarch64-unknown-linux-gnu)	40s
cargo test	8m 22s
cargo check (loongarch64-unknown-linux-musl)	39s
cargo check (powerpc-unknown-linux-gnu)	45s
cargo check (powerpc64-unknown-linux-gnu)	40s
cargo check (powerpc64le-unknown-linux-gnu)	39s
cargo check (riscv64gc-unknown-linux-gnu)	40s
cargo check (sparc64-unknown-linux-gnu)	39s
cargo check (s390x-unknown-linux-gnu)	32s
release-crate	0s
complete	1s
	21m 46s

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