Log Message:
We currently detect $MACHINE_ARCH on OpenBSD/amd64 & Bitrig/amd64 as amd64.
Bitrig uses ELF on amd64 & arm and does not have any legacy dependency on a.out.
Remove if statement to check $MACHINE_ARCH is x86_64 in-order to set $OBJECT_FMT
to ELF, preventing $OBJECT_FMT being set to a.out by mistake.

Reviewed by joerg@