Merge remote-tracking branch 'remotes/rth-gitlab/tags/pull-tcg-20210124' into staging

Merge remote-tracking branch 'remotes/rth-gitlab/tags/pull-tcg-20210124' into staging

Fix tcg constant temp overflow.
Fix running during atomic single-step.
Partial support for apple silicon.
Cleanups for accel/tcg.

# gpg: Signature made Sun 24 Jan 2021 18:08:57 GMT
# 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-gitlab/tags/pull-tcg-20210124:
  tcg: Restart code generation when we run out of temps
  tcg: Toggle page execution for Apple Silicon
  accel/tcg: Restrict cpu_io_recompile() from other accelerators
  accel/tcg: Declare missing cpu_loop_exit*() stubs
  accel/tcg: Restrict tb_gen_code() from other accelerators
  accel/tcg: Move tb_flush_jmp_cache() to cputlb.c
  accel/tcg: Make cpu_gen_init() static
  tcg: Optimize inline dup_const for MO_64
  qemu/compiler: Split out qemu_build_not_reached_always
  tcg: update the cpu running flag in cpu_exec_step_atomic

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