perf tools: Factor out feature op to process header sections

There is individual code for each feature to process header sections.

Adding a function pointer .process to struct feature_ops for keeping the
implementation in separate functions. Code to process header sections is
now a generic function.

Cc: Ingo Molnar <mingo@elte.hu>
Link: http://lkml.kernel.org/r/1328884916-5901-2-git-send-email-robert.richter@amd.com


Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>