Make linuxulator handle ELFOSABI_NONE ELF executables. Previously it was neccessary to either brand them as Linux using brandelf(1), or by adjusting kern.elf{32,64}.fallback_brand. Binaries that are correctly branded, either in the ELF header or with an ABI note, are not affected.
This can be disabled with 'sysctl compat.linux.exec_unbranded=0'. Default is to enable - unbranded binaries are still commonplace in Linux.
This fixes ldd(1) from Centos and Ubuntu.