exec: Protect map_client_list with mutex So that accesses from multiple threads are safe. Signed-off-by: Fam Zheng <famz@redhat.com> Message-Id: <1426496617-10702-4-git-send-email-famz@redhat.com> [Remove #if from cpu_exec_init_all. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>