[Fix](compile) Fix gcc compile on master (#33864)

This is imported by #33511. wrongly used

ColumnStr<T> ();

which violate C++20 standard(see https://wg21.cmeerw.net/cwg/issue2237) but still supported by clang up until now(see llvm/llvm-project#58112)

be/src/vec/columns/column_map.cpp

@@ -51,6 +51,7 @@ ColumnMap::ColumnMap(MutableColumnPtr&& keys, MutableColumnPtr&& values, Mutable
 
     if (!offsets_concrete) {
         LOG(FATAL) << "offsets_column must be a ColumnUInt64";
+        __builtin_unreachable();
     }
 
     if (!offsets_concrete->empty() && keys_column && values_column) {