Patch that implements tracepoint framework + trace buffer + monitor support.

tracing can be enabled at compile time using --enable-trace switch, 
which compiles tracing support(all of these).

Monitor commands introduced :
1. info trace : to see contents of trace buffer.
2. info tracepoints : to see available tracepoints and their status.
3. trace [on|off] : to enable / disable trace data collection.
4. tracepoint ABC [on|off] : to enable / disable traces from a specific 
tracepoint, eg ABC

-- 
Prerna Saxena

Linux Technology Centre,
IBM Systems and Technology Lab,
Bangalore, India