acl-plugin: VPP-1400: fix crash when removing a session entry
acl-plugin: VPP-1400: fix crash when removing a session entry

bihash deletion operation may in turn do underlying memory operations,
so ensure it is using the correct (private) heap.

Change-Id: Ibef7ad7f9db6fa83da02316bf7509072ce579bc0
Signed-off-by: Andrew Yourtchenko <eb6233fe2fbd585844f4fb8426b53b186ab379b1@gmail.com>
(cherry picked from commit f74b4d2b559b1d5697fd625d9c8e0f76ba5a4463)

chrisy/vpp,vpp-dev/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,vpp-dev/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,vpp-dev/vpp,FDio/vpp,vpp-dev/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,vpp-dev/vpp,vpp-dev/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,vpp-dev/vpp