perf parse-events: Make common term list to strbuf helper

perf parse-events: Make common term list to strbuf helper

A term list is turned into a string for debug output and for the str
value in the alias.

Add a helper to do this based on existing code, but then fix for
situations like events being identified.

Use strbuf to manage the dynamic memory allocation and remove the 256
byte limit.

Use in various places the string of the term list is required.

Before:

  $ sudo perf stat -vv -e inst_retired.any true
  Using CPUID GenuineIntel-6-8D-1
  intel_pt default config: tsc,mtc,mtc_period=3,psb_period=3,pt,branch
  Attempting to add event pmu 'cpu' with 'inst_retired.any,' that may result in non-fatal errors
  After aliases, add event pmu 'cpu' with 'event,period,' that may result in non-fatal errors
  inst_retired.any -> cpu/inst_retired.any/
  ...

After:

$ sudo perf stat -vv -e inst_retired.any true

  Using CPUID GenuineIntel-6-8D-1
  intel_pt default config: tsc,mtc,mtc_period=3,psb_period=3,pt,branch
  Attempt to add: cpu/inst_retired.any/
  ..after resolving event: cpu/event=0xc0,period=0x1e8483/
  inst_retired.any -> cpu/event=0xc0,period=0x1e8483/
  ...

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20230830070753.1821629-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>