Add a new interceptor: paccept(2)

Summary:
paccept(2) is a NetBSD-specific variation of accept(2).

Sponsored by <The NetBSD Foundation>

Reviewers: joerg, vitalybuka, eugenis

Reviewed By: vitalybuka

Subscribers: llvm-commits, kubamracek, #sanitizers

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D42052

llvm-svn: 323273