misc/seabios: Update to 1.16.0; use binutils binaries

Upstream release information:
https://www.seabios.org/Releases#SeaBIOS_1.15.0
https://www.seabios.org/Releases#SeaBIOS_1.16.0

When ports set USE_BINUTILS=yes, the environment is adjusted with, e.g.,
OBJDUMP=${LOCALBASE}/bin/objdump, so that binaries from devel/binutils
are used during the build.  SeaBIOS, however, ignores these environment
variables, so supply them to MAKE_ARGS.  This will fix the build when
/usr/bin/llvm-objdump is linked to /usr/bin/objdump.  See PR 267854.

PR:		267854
Approved by:	royger (maintainer)
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D37667