tcg: Change translator-side labels to a pointer

tcg: Change translator-side labels to a pointer

This is improved type checking for the translators -- it's no longer
possible to accidentally swap arguments to the branch functions.

Note that the code generating backends still manipulate labels as int.

With notable exceptions, the scope of the change is just a few lines
for each target, so it's not worth building extra machinery to do this
change in per-target increments.

Cc: Peter Maydell <[email protected]>
Cc: Edgar E. Iglesias <[email protected]>
Cc: Michael Walle <[email protected]>
Cc: Leon Alrae <[email protected]>
Cc: Anthony Green <[email protected]>
Cc: Jia Liu <[email protected]>
Cc: Alexander Graf <[email protected]>
Cc: Aurelien Jarno <[email protected]>
Cc: Blue Swirl <[email protected]>
Cc: Guan Xuetao <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Max Filippov <[email protected]>
Reviewed-by: Bastian Koppelmann <[email protected]>
Signed-off-by: Richard Henderson <[email protected]>