Make the TcParser tables constexpr.

Without it some compilers will not constant initialize the tables and cause
runtime failures during registration. We must be able to parse descriptors
during dynamic initialization.

PiperOrigin-RevId: 529092745

src/google/protobuf/compiler/cpp/parse_function_generator.cc

@@ -406,8 +406,7 @@ void ParseFunctionGenerator::GenerateTailCallTable(Formatter& format) {
   // unknown fields and potentially an extension range.
   auto field_num_to_entry_table = MakeNumToEntryTable(ordered_fields_);
   format(
-      "PROTOBUF_CONSTINIT PROTOBUF_ATTRIBUTE_INIT_PRIORITY1\n"
-      "const ::_pbi::TcParseTable<$1$, $2$, $3$, $4$, $5$> "
+      "constexpr ::_pbi::TcParseTable<$1$, $2$, $3$, $4$, $5$> "
       "$classname$::_table_ = "
       "{\n",
       tc_table_info_->table_size_log2, ordered_fields_.size(),