perf intel-pt: Accumulate cycle count from CYC packets

perf intel-pt: Accumulate cycle count from CYC packets

In preparation for providing instructions-per-cycle (IPC) information,
accumulate cycle count from CYC packets.

Although CYC packets are optional (requires config term 'cyc' to enable
cycle-accurate mode when recording), the simplest way to count cycles is
with CYC packets.

The first complication is that cycles must be counted only when also
counting instructions.

That means when control flow packet generation is enabled i.e. between
TIP.PGE and TIP.PGD packets.

Also, sampling the cycle count follows the same rules as sampling the
timestamp, that is, not before the instruction to which the decoder is
walking is reached.

In addition, the cycle count is not accurate for any but the first
branch of a TNT packet.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20190520113728.14389-6-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>