net/wmwave: fix build with -fno-common

[fuz]

Summary

net/wmwave: fix build with -fno-common

While we are at it:

 - define LICENSE
 - switch to USES=localbase
 - add missing include for errx()

PR:		267588
MFH:		2023Q1
Approved by:	build fix blanket, maintainer timeout

Test Plan

Tested on i386 amd64 FreeBSD 12.4 13.1. arm64 pending.
See http://fuz.su/~fuz/freebsd/batch1/

[flo]

Approved

[fuz]

As a general question, do you want me to obtain separate approval for the MFH commits or is this approval here also applicable to the commit to the quarterly branch?

[flo]

In D38511#877881, @fuz_fuz.su wrote:

As a general question, do you want me to obtain separate approval for the MFH commits or is this approval here also applicable to the commit to the quarterly branch?

From my side both commits are approved, as the request included the MFH tag.