Draft: ECC improvements - for desktop build

Update the framesize of the audio signal to analyze in tone detector, depending on the chosen sampling rate. The audio sample duration is then always 20 ms.

Test if a tone has really been played before the validation of the detection.

Reduce the estimated delay in order to add a margin for AEC, for all systems. The margin is computed in percent of the estimated delay.

Replace deprecated function in test_ecc.c by linphone_core_start_echo_canceller_calibration.