Order route set based on dialogs role

[jwes]

RFC 3261 specifies, that:

The route set MUST be set to the list of URIs in the Record-Route
header field from the request, taken in order and preserving all URI
parameters.

-- section 12.1.1 UAS behavior

also:

The route set MUST be set to the list of URIs in the Record-Route
header field from the response, taken in reverse order and preserving
all URI parameters.

-- section 12.1.2 UAC behavior

Currently, just the UAC behavior was taken into account backward iterating the list.

While still continuing to iterate backwards, the route is appended in front if the role is UAS.

[sauwming]

Checking the code, dlg_update_routeset() is only called from pjsip_dlg_on_rx_response(), and only if dlg->role == PJSIP_ROLE_UAC.

In fact, there's an assertion just a few lines above the patch:

if (dlg->role == PJSIP_ROLE_UAC) {
...
} else {
    pj_assert(!"Should not happen");
}

[jwes]

pjsip_method_creates_dialog does only return true on UAC's?