tools: switch to v2/3 independent bytes usage

Conform to bytes encoding for some portion of the tools/tests, such that
smoke tests pass on python3. More conversions are surely required.

Signed-off-by: Brenden Blanco <bblanco@gmail.com>
diff --git a/tools/memleak.py b/tools/memleak.py
index e47a67f..5d69538 100755
--- a/tools/memleak.py
+++ b/tools/memleak.py
@@ -471,7 +471,7 @@
                          key=lambda a: a.size)[-top_stacks:]
         for alloc in to_show:
                 print("\t%d bytes in %d allocations from stack\n\t\t%s" %
-                      (alloc.size, alloc.count, "\n\t\t".join(alloc.stack)))
+                      (alloc.size, alloc.count, b"\n\t\t".join(alloc.stack)))
 
 def print_outstanding_combined():
         stack_traces = bpf["stack_traces"]