python: import ABCs from collections.abc

Importing Abstract Base Classes (ABCs) from the collections module
is deprecated since Python 3.3, it emits a warning since Python 3.8,
and it will stop working in Python 3.10.

Try importing MutableMapping from collections.abc (the preferred way since
Python 3.3) and, in case of error (Python < 3.3) fall back to importing it
from collections.

src/python/bcc/table.py

@@ -13,7 +13,10 @@
 # limitations under the License.
 
 from __future__ import print_function
-from collections import MutableMapping
+try:
+ from collections.abc import MutableMapping
+except ImportError:
+ from collections import MutableMapping
 import ctypes as ct
 from functools import reduce
 import multiprocessing