arm: singlestep bug

[Andrew Jones]

Hello TCG developers,

We have new debug test cases in kvm-unit-tests thanks to Ricardo Koller.
The singlestep test cases are failing with TCG. Enabling TCG debug outputs
the error

  TCG hflags mismatch (current:(0x000004a1,0x0000000000004000) 
rebuilt:(0x000004a3,0x0000000000004000)

I noticed that the test passed on an older QEMU, so I bisected it and
found commit e979972a6a17 ("target/arm: Rely on hflags correct in
cpu_get_tb_cpu_state"), which unfortunately doesn't tell us anything
that the above error message didn't say already (apparently we can't
currently depend on hflags being correct wrt singlestep at this point).

Thanks,
drew