perf test: Fixup aliases checking in the 'vmlinux matches kallsyms' test

There are cases where looking at just the next and prev entries is not
enough, like with:

$ readelf -sW /usr/lib/debug/lib/modules/4.3.3-301.fc23.x86_64/vmlinux | grep ffffffff81065ec0
4979: ffffffff81065ec0 53 FUNC LOCAL DEFAULT 1 try_to_free_pud_page
4980: ffffffff81065ec0 53 FUNC LOCAL DEFAULT 1 try_to_free_pte_page
4981: ffffffff81065ec0 53 FUNC LOCAL DEFAULT 1 try_to_free_pmd_page

So just search by name to see if the symbol is in kallsyms.

Cc: Adrian Hunter <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/vmlinux-kallsyms.c

···
 	 */
 	for (nd = rb_first(&vmlinux_map->dso->symbols[type]); nd; nd = rb_next(nd)) {
 		struct symbol *pair, *first_pair;
-		bool backwards = true;
 
 		sym  = rb_entry(nd, struct symbol, rb_node);
 
···
 				continue;
 
 			} else {
-				struct rb_node *nnd;
-detour:
-				nnd = backwards ? rb_prev(&pair->rb_node) :
-						  rb_next(&pair->rb_node);
-				if (nnd) {
-					struct symbol *next = rb_entry(nnd, struct symbol, rb_node);
-
-					if (UM(next->start) == mem_start) {
-						pair = next;
+				pair = machine__find_kernel_symbol_by_name(&kallsyms, type, sym->name, NULL, NULL);
+				if (pair) {
+					if (UM(pair->start) == mem_start)
 						goto next_pair;
-					}
-				}
 
-				if (backwards) {
-					backwards = false;
-					pair = first_pair;
-					goto detour;
+					pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
+						 mem_start, sym->name, pair->name);
 				}
-
-				pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
-					 mem_start, sym->name, pair->name);
 			}
 		} else
 			pr_debug("%#" PRIx64 ": %s not on kallsyms\n",