Prepare the SDK for the new Flexisip build and packaging scripts

Parent : flexisip!545 (merged)

Enfants :

• bctoolbox!127 (merged)
• bcunit!14 (merged)
• belle-sip!216 (merged)
• belr!35 (merged)
• liblinphone!1523 (merged)
• mediastreamer2!503 (merged)
• ortp!77 (merged)