gstsctpclientsink: Lock query requests

Change-Id: If1e5518b9c460a6b6adc08b10341a8229214c9b0
gstsctpclientsink: Cancel pending requests when releasing the pipeline

Change-Id: Ib73eac68bf3d6fb233edfe03aee6f9d432765b9d
gstsctpclientsink: Send data buffers to server

Change-Id: Ib5a5ed163812157d3122a98bbdd8364731978bb2
cmake refactorization

Change-Id: I8dd3ab51eef51462e8c8380e4e077fa826ff5a94