perf config: Fix a memory leak in collect_config()

Detected with gcc's ASan:

  Direct leak of 66 byte(s) in 5 object(s) allocated from:
      #0 0x7ff3b1f32070 in __interceptor_strdup (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x3b070)
      #1 0x560c8761034d in collect_config util/config.c:597
      #2 0x560c8760d9cb in get_value util/config.c:169
      #3 0x560c8760dfd7 in perf_parse_file util/config.c:285
      xen-troops#4 0x560c8760e0d2 in perf_config_from_file util/config.c:476
      xen-troops#5 0x560c876108fd in perf_config_set__init util/config.c:661
      xen-troops#6 0x560c87610c72 in perf_config_set__new util/config.c:709
      xen-troops#7 0x560c87610d2f in perf_config__init util/config.c:718
      xen-troops#8 0x560c87610e5d in perf_config util/config.c:730
      xen-troops#9 0x560c875ddea0 in main /home/changbin/work/linux/tools/perf/perf.c:442
      xen-troops#10 0x7ff3afb8609a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)

Signed-off-by: Changbin Du <[email protected]>
Reviewed-by: Jiri Olsa <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt (VMware) <[email protected]>
Cc: Taeung Song <[email protected]>
Fixes: 20105ca ("perf config: Introduce perf_config_set class")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

tools/perf/util/config.c

@@ -633,11 +633,10 @@ static int collect_config(const char *var, const char *value,
 	}
 
 	ret = set_value(item, value);
-	return ret;
 
 out_free:
 	free(key);
-	return -1;
+	return ret;
 }
 
 int perf_config_set__collect(struct perf_config_set *set, const char *file_name,