qemu-pr-helper: Daemonize before dropping privileges

After we've dropped privileges it might be not possible to write
pidfile. For instance, if this binary is run as root (because
user wants it to write pidfile to some privileged location)
writing pidfile fails because privileges are dropped before we
even get to that.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

scsi/qemu-pr-helper.c

@@ -1081,13 +1081,6 @@ int main(int argc, char **argv)
                                          accept_client,
                                          NULL, NULL);
 
-#ifdef CONFIG_LIBCAP
-    if (drop_privileges() < 0) {
-        error_report("Failed to drop privileges: %s", strerror(errno));
-        exit(EXIT_FAILURE);
-    }
-#endif
-
     if (daemonize) {
         if (daemon(0, 0) < 0) {
             error_report("Failed to daemonize: %s", strerror(errno));
@@ -1096,6 +1089,13 @@ int main(int argc, char **argv)
         write_pidfile();
     }
 
+#ifdef CONFIG_LIBCAP
+    if (drop_privileges() < 0) {
+        error_report("Failed to drop privileges: %s", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+#endif
+
     state = RUNNING;
     do {
         main_loop_wait(false);