generated_message_tctable_decl: improve portability: avoid ambiguous bool type, use uint8_t

[barracuda156]

Fixes the failure on 32-bit powerpc:

In file included from /opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/upb/message/internal/accessors.h:22,
                 from /opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/upb/message/accessors.h:16,
                 from /opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/upb/generated_code_support.h:13,
                 from /opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/upb/reflection/cmake/google/protobuf/descriptor.upb.h:12,
                 from /opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/upb/reflection/descriptor_bootstrap.h:14,
                 from /opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/upb/reflection/common.h:15,
                 from /opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/upb/reflection/enum_def.h:14,
                 from /opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/upb/reflection/message_reserved_range.c:8:
/opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/upb/message/internal/message.h: In function 'upb_TaggedAuxPtr_Extension':
/opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/upb/message/internal/message.h:61:10: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
   61 |   return (upb_Extension*)(ptr.ptr & ~1ULL);
      |          ^
In file included from /opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/src/google/protobuf/field_mask.pb.h:23,
                 from /opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/src/google/protobuf/[field_mask.pb.cc:6](http://field_mask.pb.cc:6/):
/opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/src/google/protobuf/generated_message_tctable_decl.h:260:34: error: static assertion failed
  260 | static_assert(sizeof(MapAuxInfo) <= 8, "");
      |               ~~~~~~~~~~~~~~~~~~~^~~~
/opt/local/var/macports/build/_opt_local_ppcports_devel_protobuf/protobuf/work/protobuf-30.2/src/google/protobuf/generated_message_tctable_decl.h:260:34: note: the comparison reduces to '(12 <= 8)'

[sbenzaquen]

Can we keep the input/output of the API as bool?
We only need to change the members to be uint8_t : 1.

[barracuda156]

Yeah, I guess so. I will verify that once back to the machine and update the PR accordingly.