exec-all: Widen TranslationBlock pc and cs_base to 64-bits

This makes TranslationBlock agnostic to the address size of the guest.
Use vaddr for pc, since that's always a virtual address.
Use uint64_t for cs_base, since usage varies between guests.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>