perf tools: Rename cpu_map__all() to cpu_map__empty()

The CPU map is in an "empty" (or not-applicable) state when monitoring
specific threads.

cpu_map__all() returns true if the CPU map is in this empty state (i.e
for the 'empty_cpu_map' or if we created the map via
cpu_map__dummy_new().

The name, cpu_map__all(), is misleading, because even when monitoring
all CPUs, (eg: perf record -a), cpu_map__all() returns false.

Rename cpu_map__all() to cpu_map__empty().

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20130523012620.GA27733@us.ibm.com


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