This reverts commit 8cc46787.
It turns out that cmd->frame can be NULL and thus the commit
can cause a SIGSEGV
Reported-by: NHolger Schranz <holger@fam-schranz.de>
Cc: qemu-stable@nongnu.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>