log: do not use CONFIG_USER_ONLY

This decouples logging further from config-target.h

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

bsd-user/main.c

@@ -849,6 +849,7 @@ int main(int argc, char **argv)
     }
 
     /* init debug */
+    qemu_log_needs_buffers();
     qemu_set_log_filename(log_file);
     if (log_mask) {
         int mask;