perf record: Enable arbitrary event names thru name= modifier

Enable complex event names containing [.:=,] symbols to be encoded into Perf
trace using name= modifier e.g. like this:

  perf record -e cpu/name=\'OFFCORE_RESPONSE:request=DEMAND_RFO:response=L3_HIT.SNOOP_HITM\',\
		  period=0x3567e0,event=0x3c,cmask=0x1/Duk ./futex

Below is how it looks like in the report output. Please note explicit escaped
quoting at cmdline string in the header so that thestring can be directly reused
for another collection in shell:

perf report --header

  # ========
  ...
  # cmdline : /root/abudanko/kernel/tip/tools/perf/perf record -v -e cpu/name=\'OFFCORE_RESPONSE:request=DEMAND_RFO:response=L3_HIT.SNOOP_HITM\',period=0x3567e0,event=0x3c,cmask=0x1/Duk ./futex
  # event : name = OFFCORE_RESPONSE:request=DEMAND_RFO:response=L3_HIT.SNOOP_HITM, , type = 4, size = 112, config = 0x100003c, { sample_period, sample_freq } = 3500000, sample_type = IP|TID|TIME, disabled = 1, inh
  ...
  # ========
  #
  #
  # Total Lost Samples: 0
  #
  # Samples: 24K of event 'OFFCORE_RESPONSE:request=DEMAND_RFO:response=L3_HIT.SNOOP_HITM'
  # Event count (approx.): 86492000000
  #
  # Overhead  Command  Shared Object     Symbol
  # ........  .......  ................  ..............................................
  #
      14.75%  futex    [kernel.vmlinux]  [k] __entry_trampoline_start
...

  perf stat -e cpu/name=\'CPU_CLK_UNHALTED.THREAD:cmask=0x1\',period=0x3567e0,event=0x3c,cmask=0x1/Duk ./futex

  10000000 process context switches in 16678890291ns (1667.9ns/ctxsw)

   Performance counter stats for './futex':

      88,095,770,571      CPU_CLK_UNHALTED.THREAD:cmask=0x1

        16.679542407 seconds time elapsed

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/c194b060-761d-0d50-3b21-bb4ed680002d@linux.intel.com


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