Using SwiftPM with system C library

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I translating it into Swift and make it building success.
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The <sys/socket.s> looks like could import via:
import Darwin.POSIX.sys.socket

However, the test build is not passing due to other library not linked. That is a lib named "libresolv.tbd" which contains <dns.h>. But I have no idea how to do it. The tbd file is not a normal lib.

How to link such a library in SwiftPM?