git: Kernel ELF: Restore legacy FreeBSD brand

[Thomas Nikolajsen]

>>Re. /usr/libexec/ld-elf.so.1, it is installed on my system,
>>seems like they are changed on installworld (mtime changed);
>>anyway they aren't removed on upgrade ('make upgrade'),
>>so all hosts which has been source upgraded for a few years will have file. 
>
>Why don't we build ld-elf.so.1 anymore? Can't we bring it back?

/usr/libexec/ld-elf.so.1 is installed by default, it is installed from lib/compat/i386.

I'm not sure we will have any benefit building it in build(7).

 -thomas