perf tools: Add a 'struct map_groups' pointer to 'struct map_symbol'

And fill it whenever we setup a a 'struct map_symbol', now we need to
use it, next cset.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-fzwfcnddenz1o7uj1fzw3g46@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/unwind-libdw.c

@@ -81,6 +81,7 @@ static int entry(u64 ip, struct unwind_info *ui)
 		return -1;
 
 	e->ip	  = ip;
+	e->ms.mg  = al.mg;
 	e->ms.map = al.map;
 	e->ms.sym = al.sym;