QSV: remove dead code.
QSV: separate detection of Media SDK availability from that of the minimum version.

This way, we can log whether Media SDK is available,
even if it doesn't work for us (e.g. driver too old).
QSV: decouple capability-querying code from hb_qsv_info_init.

This will enable us to query capabilities multiple times,
e.g. whenever the preferred implementation is modified.
Work in progress.
Not making much progress.
Getting somewhere?
Cosmetics.
More debug.
Trial.
Fix.
Test.
Prettyprint.
Works a bit better.
Fix.
Cosmetics.
More cosmetics.
API 1.8 version 1.0.
Rename.
Fix.
Misc.