perf tools: Use tid in mmap/mmap2 events to find maps

Now that we can properly synthesize threads system-wide, make sure the
mmap and mmap2 events use tids instead of pids to locate their maps.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1393429527-167840-3-git-send-email-dzickus@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>