libsearpc: Update to 3.2.0, add Python 3 bindings package

This also moves the Python dependency from libsearpc to python3-searpc,
and adds myself as a maintainer.

Patches:
* 001-fix-memory-leak-GH-48.patch: This is (at this time) the only
  difference between the tags v3.2.0 and v3.2-latest.

* 002-no-future-import.patch: The future package is only needed for
  Python 2 compatibility; all of the functions/symbols it provides are
  available in Python 3.

Signed-off-by: Jeffery To <jeffery.to@gmail.com>

libs/libsearpc/patches/001-fix-memory-leak-GH-48.patch

@@ -0,0 +1,19 @@
+From 9b2e2dc65213fb22ed400dc54e4c2279564df62b Mon Sep 17 00:00:00 2001
+From: ly1217 <yu.liu@seafile.com>
+Date: Thu, 31 Oct 2019 00:31:38 -0700
+Subject: [PATCH] Fix memory leak.
+
+---
+ lib/searpc-named-pipe-transport.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+--- a/lib/searpc-named-pipe-transport.c
++++ b/lib/searpc-named-pipe-transport.c
+@@ -377,6 +377,7 @@ void searpc_free_client_with_pipe_transp
+     close(pipe_client->pipe_fd);
+ #endif
+     g_free (pipe_client);
++    g_free (data->service);
+     g_free (data);
+     searpc_client_free (client);
+ }

libs/libsearpc/patches/002-no-future-import.patch

@@ -0,0 +1,11 @@
+--- a/pysearpc/named_pipe.py
++++ b/pysearpc/named_pipe.py
+@@ -2,8 +2,6 @@
+ RPC client/server implementation based on named pipe transport.
+ """
+ 
+-from future import standard_library
+-standard_library.install_aliases()
+ from builtins import object
+ import json
+ import logging