We now build pjsip from our own android makefiles, we can generate an apk
compatible simultaneously with arm and x86.

Refs #40953

The modifications in SFLphone RTP layer need to be integrated when building
android client.

Refs #40020

Integration of new security features implies modifications in call handling.
By default, when handling a call,  a SipCall object is created, but if ZRTP hooks
are activated, the call is dynamically subclassed, and becomes a SecureSipCall.

Refs #40939

This commit introduces a new class holding references to the security state of
a call.

Refs #40939

SipCall keeps track of its security state, and store its SAS if needed.
This commit also introduce two new Fragments wrappers, for accounts and calls.
These wrappers reduce code duplication between fragments requiring hooks on daemon
signals.

preferences

There are still some missing traductions in general account settings.

Bug introduced in rev 822ca2e9.

Custom File Explorer dialog has been dropped, we will delegate this action to
third party app, or to the Storage Application Framework (new in API 19).

Available on API 17 +

libccrtp was depending on commoncpp2, and have been replaced by a version
depending on ucommon as well.