libperf: Add API for allocating new thread map array

The existing API perf_thread_map__new_dummy() allocates new thread map
for one thread. I couldn't find a way to reallocate the map with more
threads, or to allocate a new map for more than one thread.

Having multiple threads in a thread map is essential for some use cases.
That's why a new API is proposed, which allocates a new thread map for
given number of threads: perf_thread_map__new_array()

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/linux-perf-users/20220221102628.43904-1-tz.stoyanov@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

libperf: Rename arguments of perf_thread_map APIs

The "int thread" input arguments of some perf_thead_map APIs are index
of the thread in the thread map.

In order to avoid confusion and to make the APIs consistent with
perf_cpu_map APIs, those arguments are renamed to "int idx".

Suggested-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20220221102612.43879-1-tz.stoyanov@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

libperf: Move to tools/lib/perf

Move libperf from its current location under tools/perf to a separate
directory under tools/lib/.

Also change various paths (mainly includes) to reflect the libperf move
to a separate directory and add a new directory under MANIFEST.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191206210612.8676-2-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>