perf symbols: Record whether a symbol is an alias for an IFUNC symbol

To assist with synthesizing plt symbols for IFUNCs, record whether a
symbol is an alias of an IFUNC symbol.

Reviewed-by: Namhyung Kim <[e-mail]>
Signed-off-by: Adrian Hunter <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/symbol.c

···
 			continue;
 
 		if (choose_best_symbol(curr, next) == SYMBOL_A) {
+			if (next->type == STT_GNU_IFUNC)
+				curr->ifunc_alias = true;
 			rb_erase_cached(&next->rb_node, symbols);
 			symbol__delete(next);
 			goto again;
 		} else {
+			if (curr->type == STT_GNU_IFUNC)
+				next->ifunc_alias = true;
 			nd = rb_next(&curr->rb_node);
 			rb_erase_cached(&curr->rb_node, symbols);
 			symbol__delete(curr);

tools/perf/util/symbol.h

···
 	u8		inlined:1;
 	/** Has symbol__annotate2 been performed. */
 	u8		annotate2:1;
+	/** Symbol is an alias of an STT_GNU_IFUNC */
+	u8		ifunc_alias:1;
 	/** Architecture specific. Unused except on PPC where it holds st_other. */
 	u8		arch_sym;
 	/** The name of length namelen associated with the symbol. */