Don't configure the wakeup handler when a vCPU is blocking with IRQs
disabled, in which case any IRQ, posted or otherwise, should not be
recognized and thus should not wake the vCPU.

Fixes: bf9f6ac8 ("KVM: Update Posted-Interrupts Descriptor when vCPU is blocked")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>