ucalls: convert bytes to str

This fixes the following error with python3

Tracing calls in process 2577 (language: python)... Ctrl-C to quit.
^C
Traceback (most recent call last):
  File "/usr/share/bcc/tools/lib/ucalls", line 303, in <module>
    data = get_data()   # [(function, (num calls, latency in ns))]
  File "/usr/share/bcc/tools/lib/ucalls", line 264, in get_data
    bpf["counts"].items()))
  File "/usr/share/bcc/tools/lib/ucalls", line 262, in <lambda>
    data = list(map(lambda kv: (kv[0].clazz + "." + kv[0].method,
TypeError: can't concat str to bytes

Signed-off-by: Rafael Fonseca <[email protected]>

tools/lib/ucalls.py

@@ -255,11 +255,13 @@
 def get_data():
  # Will be empty when no language was specified for tracing
  if args.latency:
- data = list(map(lambda kv: (kv[0].clazz + "." + kv[0].method,
+ data = list(map(lambda kv: (kv[0].clazz.decode() + "." + \
+ kv[0].method.decode(),
  (kv[1].num_calls, kv[1].total_ns)),
  bpf["times"].items()))
  else:
- data = list(map(lambda kv: (kv[0].clazz + "." + kv[0].method,
+ data = list(map(lambda kv: (kv[0].clazz.decode() + "." + \
+ kv[0].method.decode(),
  (kv[1].value, 0)),
  bpf["counts"].items()))