Merge remote-tracking branch 'remotes/rth/tags/pull-tcg-20181031' into staging

Track mmu_idx for which the TLB is clean and need not be flushed again.

# gpg: Signature made Wed 31 Oct 2018 12:19:31 GMT
# gpg:                using RSA key 64DF38E8AF7E215F
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>"
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth/tags/pull-tcg-20181031:
  cputlb: Remove tlb_c.pending_flushes
  cputlb: Filter flushes on already clean tlbs
  cputlb: Count "partial" and "elided" tlb flushes
  cputlb: Merge tlb_flush_page into tlb_flush_page_by_mmuidx
  cputlb: Merge tlb_flush_nocheck into tlb_flush_by_mmuidx_async_work
  cputlb: Move env->vtlb_index to env->tlb_d.vindex
  cputlb: Split large page tracking per mmu_idx
  cputlb: Move cpu->pending_tlb_flush to env->tlb_c.pending_flush
  cputlb: Remove tcg_enabled hack from tlb_flush_nocheck
  cputlb: Move tlb_lock to CPUTLBCommon

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