perf hists: Remove needless global col lenght calcs

perf hists: Remove needless global col lenght calcs

To support multiple events we need to do these calcs per 'struct hists'
instance, and it turns out we already do that at:

	__hists__add_entry
		hists__inc_nr_entries
			hists__calc_col_len

for all the unfiltered hist_entry instances we stash in the rb tree, so
trow away the dead code.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>