sql/field.cc:
  Field_geom::store() returns -1 as a sign of fatal error
sql/field_conv.cc:
  set_field_to_null* return -1 now as the fatal error
sql/item.cc:
  no sign inversions needed
sql/opt_range.cc:
  -1 is the sign of fatal error now
sql/sql_base.cc:
  -1 is the fatal error