Contributing FreeBSD/aarch64 support

[Ed Maste]

I would like to contribute FreeBSD/aarch64 support for binutils. The
work is straightforward, and consists largely of adding new case
statements and Makefile adjustments.  Several different people are
responsible for parts of this change.

The patch as it stands now can be seen in a commit in my repository on
github[1]; the diffstat summary is:

 bfd/config.bfd                |    5 +++++
 bfd/configure                 |    2 +-
 gas/config/tc-aarch64.c       |    3 ---
 gas/configure                 |    2 +-
 ld/Makefile.am                |   10 ++++++++++
 ld/Makefile.in                |   12 ++++++++++++
 ld/configure                  |    2 +-
 ld/configure.tgt              |    2 ++
 ld/emulparams/aarch64fbsd.sh  |   37 +++++++++++++++++++++++++++++++++++++
 ld/emulparams/aarch64fbsdb.sh |    2 ++

The substantial change is the addition of aarch64fbsd.sh; it is almost
entirely a copy of an existing emulparams file.  I've seen reference
to small changes being acceptable without copyright assignment
paperwork, and would like to know whether it's feasible to accept this
change under those terms.

[1] https://github.com/emaste/binutils-gdb/commit/a7626f844fd7de213e429decb3ec430adc3498d3.patch