CLEANUP: mux-quic: rename internal functions

This patch is similar to the previous one but for QUIC mux functions
used inside the mux code itself or application layer. Replace all
occurences of qc_* prefix by qcc_* or qcs_*. This should help to better
differentiate code between quic_conn and MUX.

This should be backported up to 2.7.
4 files changed