perf tools: Add perf data cache feature

Storing CPU cache details under perf data. It's stored as new
HEADER_CACHE feature and it's displayed under header info with -I
option:

  $ perf report --header-only -I
  ...
  # CPU cache info:
  #  L1 Data                 32K [0-1]
  #  L1 Instruction          32K [0-1]
  #  L1 Data                 32K [2-3]
  #  L1 Instruction          32K [2-3]
  #  L2 Unified             256K [0-1]
  #  L2 Unified             256K [2-3]
  #  L3 Unified            4096K [0-3]
  ...

All distinct caches are stored/displayed.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20160216150143.GA7119@krava.brq.redhat.com
[ Fixed leak on process_caches(), s/cache_level/cpu_cache_level/g ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>