runtime-perf: add linux perf events

This introduces support for the linux perf API. This enables and
exposes the follow block level performance counters through ctrlport
    * L1 Data-Cache Miss Rate
    * Branch Mispredict Rate
    * CPU cycles (not subject to freq scaling)
    * SW Context Switches
    * SW CPU Migrations

Note that in cmake we need to explicitly check for required headers because
they may not always be there (ex: ubuntu 12.04 doesn't package
a generic hw_breakpoint.h)
runtime: add throughput performance counter
ctrlport: fancy mods to perf-monitorx from march hackfest

(Plus some bug and stylistic fixes to previous work)