OpenBSD/i386 uses elf_i386_obsd for the emulation linker.

Signed-off-by: Brad Smith <brad@comstyle.com>
Message-id: 20171107234608.GA395@humpty.home.comstyle.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>