perf block: Cleanup and refactor block info functions

We have already implemented some block-info related functions.
Now it's time to do some cleanup, refactoring and move the
functions and structures to new block-info.h/block-info.c.

 v4:
 ---
 Move code for skipping column length calculation to patch:
 'perf diff: Don't use hack to skip column length calculation'

 v3:
 ---
 1. Rename the patch title
 2. Rename from block.h/block.c to block-info.h/block-info.c
 3. Move more common part to block-info, such as
    block_info__process_sym.
 4. Remove the nasty hack for skipping calculation of column
    length

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191107074719.26139-3-yao.jin@linux.intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>