- voutgl.m: misc cleanup, reworked context locking as well as enabling double buffering for faster rendering

to JavaScript API implementation.

Integrity Transform Carrying Roll-Over Counter for SRTP

Once debugged, it should provide a simple way to synchronize live
(multicast...) secure streams.

(unless the assertion is false, which is not the case here)

This seems to be the (stupid) way it has to be done - closes #670

- Require automake 1.9 to fix some libtool plugin build problems
- Remove useless libs/Makefile

This is not very useful at the moment, but will be needed for proper
replay attack protection

It has to be at least 64, and it is too complicated to implement a bigger
value, so it's not going to be configurable

Revert [19273] because these asserts are meant to catch serious programming errors. Thanks zorglub for enlightning me.