tcg: Improve tcg_out_label and fix its usage for w64

tcg: Improve tcg_out_label and fix its usage for w64

tcg_out_label is always called with a third argument of pointer type
which was casted to tcg_target_long.

These casts can be avoided by changing the prototype of tcg_out_label.

There was also a cast to long. For most hosts with
sizeof(long) == sizeof(tcg_target_long) == sizeof(void *) this did not
matter, but for w64 it was wrong. This is fixed now.

Cc: Blue Swirl <blauwirbel@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>