In uses like 'perf inject' it is not necessary to gather the symbol for
each call chain location, the map for the sample IP is wanted so that
build IDs and the like can be injected. Make gathering the symbol in the
callchain_cursor optional.

For a 'perf inject -B' command this lowers the peak RSS from 54.1MB to
29.6MB by avoiding loading symbols.
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Anne Macedo <retpolanne@posteo.net>
Cc: Casey Chen <cachen@purestorage.com>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sun Haiyong <sunhaiyong@loongson.cn>
Link: https://lore.kernel.org/r/20240909203740.143492-5-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>