perf hists: Separate overhead and baseline columns

perf hists: Separate overhead and baseline columns

Currently the overhead and baseline columns are handled within single
function and the distinction is made by 'baseline hists' pointer passed
by 'struct perf_hpp::ptr'.

Since hists pointer is now part of each hist_entry, it's possible to
locate paired hists pointer directly from the passed struct hist_entry
pointer.

Also separating those 2 columns makes the code more obvious.

Signed-off-by: Jiri Olsa <[email protected]>
Cc: Corey Ashford <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>