fix numa-related (and kernel-dependent) test failures

fix numa-related (and kernel-dependent) test failures

This change is required on some kernels due to the way a change in
the kernel's CONFIG_NR_CPUS propagates through the numa library.
* src/qemu_conf.c (qemudCapsInitNUMA): Pass numa_all_cpus_ptr->size/8
as the buffer-length-in-bytes in the call to numa_node_to_cpus, since
that's what is required on second and subseqent calls.
* src/uml_conf.c (umlCapsInitNUMA): Likewise.