Code should not link to `sys/cdefs.h` (see https://wiki.musl-libc.org/faq.html#Q:-When-compiling-something-against-musl,-I-get-error-messages-about-%3Ccode%3Esys/cdefs.h%3C/code%3E ) (apologies for the awful link). The link above includes the necessary fix.
I sent a patch for this and it was accepted on June 11: https://mails.dpdk.org/archives/dev/2018-June/103971.html