perf record: Avoid synthesizing mmap() for all processes in per-thread mode

perf record: Avoid synthesizing mmap() for all processes in per-thread mode

A bug was introduced by commit c45c6ea2e5c57960dc67e00294c2b78e9540c007.

Perf record was scanning /proc/PID to create synthetic PERF_RECOR_MMAP
entries even though it was running in per-thread mode. There was a bogus
check to select what mmaps to synthesize. We only need all processes in
system-wide mode.

Cc: David S. Miller <davem@davemloft.net>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
LKML-Reference: <4c192107.4f1ee30a.4316.fffff98e@mx.google.com>
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>