Introduce qemu_guest_getrandom.
Use qemu_guest_getrandom in aspeed, nrf51, bcm2835, exynos4210 rng devices.
Use qemu_guest_getrandom in target/ppc darn instruction.
Support ARMv8.5-RNG extension.
Support x86 RDRAND extension.

Acked-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Laurent Vivier <laurent@vivier.eu>

# gpg: Signature made Wed 22 May 2019 19:36:43 BST
# gpg:                using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg:                issuer "richard.henderson@linaro.org"
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [full]
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth/tags/pull-rng-20190522: (25 commits)
  target/i386: Implement CPUID_EXT_RDRAND
  target/ppc: Use qemu_guest_getrandom for DARN
  target/ppc: Use gen_io_start/end around DARN
  target/arm: Implement ARMv8.5-RNG
  target/arm: Put all PAC keys into a structure
  hw/misc/exynos4210_rng: Use qemu_guest_getrandom
  hw/misc/bcm2835_rng: Use qemu_guest_getrandom_nofail
  hw/misc/nrf51_rng: Use qemu_guest_getrandom_nofail
  aspeed/scu: Use qemu_guest_getrandom_nofail
  linux-user: Remove srand call
  linux-user/aarch64: Use qemu_guest_getrandom for PAUTH keys
  linux-user: Use qemu_guest_getrandom_nofail for AT_RANDOM
  linux-user: Call qcrypto_init if not using -seed
  linux-user: Initialize pseudo-random seeds for all guest cpus
  cpus: Initialize pseudo-random seeds for all guest cpus
  util: Add qemu_guest_getrandom and associated routines
  ui/vnc: Use gcrypto_random_bytes for start_auth_vnc
  ui/vnc: Split out authentication_failed
  crypto: Change the qcrypto_random_bytes buffer type to void*
  crypto: Use getrandom for qcrypto_random_bytes
  ...

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