In gimp_config_deserialize_fundamental(), we can't use
g_value_set_static_string() because that will in the end pass the
GScanner's temporary scanner->value.v_string to
GObject::set_property(), and depending on set_property()'s
implementation, we might not dup the string (for example objects
created via gimp_config_type_register() will simply use g_value_copy()
and end up with a dangling pointer as a string member).
(cherry picked from commit 2e6656599d)
72033f7493