Building world and kernel on RPI3 B+ compilation failure, unwind-dw2.c.

[Brian Bostwick]

I ran the following to get to the revision I am at:

*svnlite checkout https://svn.freebsd.org/base/
<https://svn.freebsd.org/base/>releng/12.1 /usr/src*

I then did a *snvlite update /usr/src before I got started today.*