syscall: use stringslite.Has{Prefix,Suffix}

syscall: use stringslite.Has{Prefix,Suffix}

Change-Id: I393191b95eeb8e17345ce28cfa1fb54a3ef13951
Reviewed-on: https://go-review.googlesource.com/c/go/+/582237
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Reviewed-by: Damien Neil <dneil@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
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