spapr/rtas: Force big endian compile for rtas

At the moment the rtas's Makefile uses generic QEMU rules which means
that when QEMU is compiled on a little endian system, the spapr-rtas.bin
is compiled as little endian too which is incorrect as it is always
executed in big endian mode.

This enforces -mbig by defining %.o:%.S rule as spapr-rtas.bin is
a standalone guest binary which should not depend on QEMU flags anyway.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-Id: <20190612020723.96802-1-aik@ozlabs.ru>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
1 file changed