perf inject: Add support for injecting guest sideband events

Inject events from a perf.data file recorded in a virtual machine into
a perf.data file recorded on the host at the same time.

Only side band events (e.g. mmap, comm, fork, exit etc) and build IDs are
injected.  Additionally, the guest kcore_dir is copied as kcore_dir__
appended to the machine PID.

This is non-trivial because:
 o It is not possible to process 2 sessions simultaneously so instead
 events are first written to a temporary file.
 o To avoid conflict, guest sample IDs are replaced with new unused sample
 IDs.
 o Guest event's CPU is changed to be the host CPU because it is more
 useful for reporting and analysis.
 o Sample ID is mapped to machine PID which is recorded with VCPU in the
 id index. This is important to allow guest events to be related to the
 guest machine and VCPU.
 o Timestamps must be converted.
 o Events are inserted to obey finished-round ordering.

The anticipated use-case is:
 - start recording sideband events in a guest machine
 - start recording an AUX area trace on the host which can trace also the
 guest (e.g. Intel PT)
 - run test case on the guest
 - stop recording on the host
 - stop recording on the guest
 - copy the guest perf.data file to the host
 - inject the guest perf.data file sideband events into the host perf.data
 file using perf inject
 - the resulting perf.data file can now be used

Subsequent patches provide Intel PT support for this.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: kvm@vger.kernel.org
Link: https://lore.kernel.org/r/20220711093218.10967-25-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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