JS2x: Check whether biosemu has been executed successfully
JS2x: Check whether biosemu has been executed successfully

The code did not check whether biosemu has been executed successfully - and
this of course caused problems when SLOF has been compiled without biosemu
enabled.

Signed-off-by: Thomas Huth <9e65be74847981e55b2564b6266c57d86d3bac05@linux.vnet.ibm.com>

qemu/SLOF,dgibson/SLOF,k0da/SLOF,k0da/SLOF,stefanberger/SLOF-tpm,dgibson/SLOF,open-power-host-os/slof,k0da/SLOF,agraf/SLOF,leilihh/SLOF,qemu/SLOF,dgibson/SLOF,mdroth/SLOF,open-power-host-os/slof,aik/SLOF,stefanberger/SLOF-tpm,aik/SLOF,leilihh/SLOF,agraf/SLOF,leilihh/SLOF,agraf/SLOF,mdroth/SLOF,stefanberger/SLOF-tpm,open-power-host-os/slof,dgibson/SLOF,mdroth/SLOF,mdroth/SLOF,aik/SLOF,open-power-host-os/slof,qemu/SLOF,leilihh/SLOF,k0da/SLOF,agraf/SLOF