perf build-id: Fix memory leak in print_sdt_events()

Detected with gcc's ASan:

  Direct leak of 4356 byte(s) in 120 object(s) allocated from:
      #0 0x7ff1a2b5a070 in __interceptor_strdup (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x3b070)
      rib#1 0x55719aef4814 in build_id_cache__origname util/build-id.c:215
      rib#2 0x55719af649b6 in print_sdt_events util/parse-events.c:2339
      rib#3 0x55719af66272 in print_events util/parse-events.c:2542
      rib#4 0x55719ad1ecaa in cmd_list /home/changbin/work/linux/tools/perf/builtin-list.c:58
      rib#5 0x55719aec745d in run_builtin /home/changbin/work/linux/tools/perf/perf.c:302
      rib#6 0x55719aec7d1a in handle_internal_command /home/changbin/work/linux/tools/perf/perf.c:354
      rib#7 0x55719aec8184 in run_argv /home/changbin/work/linux/tools/perf/perf.c:398
      rib#8 0x55719aeca41a in main /home/changbin/work/linux/tools/perf/perf.c:520
      rib#9 0x7ff1a07ae09a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Fixes: 40218da ("perf list: Show SDT and pre-cached events")
Link: http://lkml.kernel.org/r/20190316080556.3075-7-changbin.du@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Author: changbindu

tools/perf/util/build-id.c

@@ -185,6 +185,7 @@ char *build_id_cache__linkname(const char *sbuild_id, char *bf, size_t size)
 	return bf;
 }
 
+/* The caller is responsible to free the returned buffer. */
 char *build_id_cache__origname(const char *sbuild_id)
 {
 	char *linkname;

tools/perf/util/parse-events.c

@@ -2342,6 +2342,7 @@ void print_sdt_events(const char *subsys_glob, const char *event_glob,
 				printf("  %-50s [%s]\n", buf, "SDT event");
 				free(buf);
 			}
+			free(path);
 		} else
 			printf("  %-50s [%s]\n", nd->s, "SDT event");
 		if (nd2) {