Don't use EV_SYSFLAGS on OpenBSD #494

Job	Run time
Docs	8s
Clippy	17s
Check (aarch64-apple-ios)	29s
CheckTargets	1m 16s
Check (aarch64-apple-tvos)	29s
MinimalVersions (ubuntu-latest)	18s
MSRV (ubuntu-latest)	10s
Check (aarch64-unknown-openbsd)	29s
MinimalVersions (macos-latest)	24s
Check (arm64_32-apple-watchos)	29s
MSRV (macos-latest)	17s
Nightly	20s
Check (armv7-sony-vita-newlibeabihf)	30s
MSRV (windows-latest)	36s
MinimalVersions (windows-latest)	41s
Check (sparcv9-sun-solaris)	33s
Rustfmt	6s
Check (x86_64-pc-solaris)	30s
Sanitizer (address)	44s
Test (ubuntu-latest)	40s
Check (x86_64-unknown-dragonfly)	31s
Sanitizer (leak)	39s
Test (macos-latest)	41s
Check (x86_64-unknown-openbsd)	33s
TestPoll	27s
Sanitizer (memory)	1m 6s
Test (windows-latest)	2m 26s
Sanitizer (thread)	41s
TestWakerPipe	29s
Passed	1s
	17m 0s

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