perf tools: Fix type for evsel->ids and add size check for ids

Use same type for ids everywhere.

In case of writing to perf.data the size is u32. In pipe mode it is
limited to header.size (less than u16). Adding a size check here.

Size overflow due to casting shouldn't actually happen in practice, but
during development this may cause type missmatch warninngs/errors,
unifying types avoids this.

Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1345144224-27280-2-git-send-email-robert.richter@amd.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>