libperf: Add perf_cpu_map__new()/perf_cpu_map__read() functions

Moving the following functions from tools/perf:

  cpu_map__new()
  cpu_map__read()

to libperf with the following names:

  perf_cpu_map__new()
  perf_cpu_map__read()

Committer notes:

Fixed up this one:

  tools/perf/arch/arm/util/cs-etm.c

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190721112506.12306-44-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/lib/include/internal/cpumap.h

@@ -10,4 +10,8 @@ struct perf_cpu_map {
 	int		map[];
 };
 
+#ifndef MAX_NR_CPUS
+#define MAX_NR_CPUS	2048
+#endif
+
 #endif /* __LIBPERF_INTERNAL_CPUMAP_H */