dvbin: Fixup bad if-macro, document what is the main difference in the new S2API, define a new macro "DVB_USE_S2API" to be used to switch to S2API if available.
dvb_tune: (DVB-S) Allow demuxers to buffer, discard stale QPSK events and add S2API-support.
Inspiration taken from the szap-s2 implementation.
S2API is only used if available and for DVB-S cards - it might also be useful to have that for DVB-T2 / DVB-C2 tuning later, but I do not have the HW / no DVB-T2 broadcasting station nearby to test functionality.
This should do no functional changes, only usage of the different API. The S2API is more extensible and a requirement for all the HD-deliveries (e.g. DVB-S2) and since 2.6.28 is the successor of the old API.
Tuning to DVB-S2 channels actually already "works" like this if the delivery is hardcoded in - for a fully working implementation, the channels.conf.sat would need an additional field indicating the delivery type (VDR-type channels.conf have that).
This commit also:
- Cleans up some debug output.
- Moves an unneeded usleep(100000) (only needed for diseqc switching for SAT) into the DVB-S-only part of the implementation.