bcc/ld86/as86 are necessary when we build ROMBIOS. However if we do not
build it (and are not building qemu-trad), the build requirements are
overly strict and can lead to failures.
Signed-off-by: Doug Goldstein <cardoe@cardoe.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>