Allow attributes to be set where they are not allowed?

[ekr]

void
SipccSdpAttributeList::SetAttribute(SdpAttribute* attr) {
if (attr->GetType() == SdpAttribute::kOtherAttribute) {
mOtherAttributes.push_back(attr);
} else {
// TODO: Should we be willing to set attributes somewhere they are not
// allowed?
RemoveAttribute(attr->GetType());
mAttributes[attr->GetType()] = attr;
}
}