libbsd kernel namespace generation

[Chris Johns]

Hello,

Libbsd uses the pre-processor to map all the kernel calls into a libbsd kernel
name space by prepending _bsd_ to each symbol. The script ...

https://git.rtems.org/rtems-libbsd/tree/create-kernel-namespace.sh?h=6-freebsd-12

... generates the list and the result is pushed into the repo. The symbols need
to be regenerated when new sources are added into the `freebsd` tree.

The script has a few issues:

1. Objdump does not work on FreeBSD for different archs.

2. Binutils is being removed from FreeBSD base.

3. A number of BSPs need to be built to cover all the possible symbols

I would like to document the list of BSPs a generate needs to cover. I propose:

 arm/xilinx_zynq_a9_qemu
 aarch64/xilinx_versal_lp64_qemu
 i386/pc686
 powerpc/mvme2307
 sparc/erc32

Also the documentation says to use `git add -p` to add the changes. How does an
interactive add help?

Thanks
Chris