perf tools: Add perf pmu object to access pmu format definition

Adding pmu object which provides interface to pmu's sysfs
event format definition located at:
  ${sysfs_mount}/bus/event_source/devices/${pmu}/format

Following interface is exported:
  struct perf_pmu* perf_pmu__find(char *name);
  - this function returns pmu object, which is then
    passed as a handle to other interface functions

  int perf_pmu__config(struct perf_pmu *pmu, struct perf_event_attr *attr,
                       struct list_head *head_terms);
  - this function configures perf_event_attr struct based
    on pmu's format definitions and config terms data,
    containined in head_terms list.

Parser generator is used to retrive the pmu's format definition.
The generated parser is part of the patch. Added makefile rule
'pmu-parser' to generate the parser code out of the bison/flex
sources.

Added builtin test 'Test perf pmu format parsing', which could
be run like:
	perf test pmu

Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/n/tip-errz96u1668gj9wlop1zhpht@git.kernel.org


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