Abort on byte_update(pointer)

Just ignoring them would yield unsound results.

Author: tautschnig

src/solvers/flattening/bv_pointers.cpp

@@ -441,6 +441,12 @@ bvt bv_pointerst::convert_pointer_type(const exprt &expr)
   {
     return SUB::convert_byte_extract(to_byte_extract_expr(expr));
   }
+  else if(
+    expr.id() == ID_byte_update_little_endian ||
+    expr.id() == ID_byte_update_big_endian)
+  {
+    throw "byte-wise updates of pointers are unsupported";
+  }
 
   return conversion_failed(expr);
 }