Currently it looks up global variables from the current CU using address
and name.  But it sometimes fails to find a variable as the variable can
come from a different CU - but it's still strange it failed to find a
declaration for some reason.

Anyway, it can collect all global variables from all CU once and then
lookup them later on.  This slightly improves the success rate of my
test data set.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240502060011.1838090-3-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>