Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging

Fixes for two bad bugs.  For 2.4-rc0.

# gpg: Signature made Thu Jul  9 15:54:19 2015 BST using RSA key ID 78C7AE83
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>"
# gpg:                 aka "Paolo Bonzini <pbonzini@redhat.com>"
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4  E2F7 7E15 100C CD36 69B1
#      Subkey fingerprint: F133 3857 4B66 2389 866C  7682 BFFB D25F 78C7 AE83

* remotes/bonzini/tags/for-upstream:
  crypto: fix builtin qcrypto_cipher_free
  migration: fix RCU deadlock

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>