CONFIG_LEON3 added to default-configs/sparc-softmmu.mak.

Signed-off-by: Ákos Kovács <akoskovacs@gmx.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20190202072456.6468-15-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>