libipt, ild: refactor vex decode
libipt, ild: refactor vex decode

Make the c4 and c5 VEX decoders look like the EVEX decoder.

Change-Id: I9bb41a4274b12c80e07c653bae122d3ed1bd82b7
Signed-off-by: Markus Metzger <5f675b2b36595f90898e014b548ff7d9bbff2ab7@intel.com>

01org/processor-trace,01org/processor-trace,01org/processor-trace