ipmr: ip6mr: Create new sockopt to clear mfc cache only

[Callum Sinclair]

Created a way to clear the multicast forwarding cache on a socket
without having to either remove the entries manually using the delete
entry socket option or destroy and recreate the multicast socket.

Using the flags MRT_FLUSH_ENTRIES and MRT_FLUSH_VIFS, all multicast
entries can be cleared, all multicast interfaces can be closed or both
can be cleared using one sockopt call.

Patch Set 2:
  - Fix Compile Errors

Patch Set 3:
  - Fix Style Errors

Patch Set 4:
  - Implemented a way to clear the entries or vifs based off an input flag.


Callum Sinclair (1):
  ipmr: ip6mr: Create new sockopt to clear mfc cache only

 include/uapi/linux/mroute.h  |  7 +++-
 include/uapi/linux/mroute6.h |  7 +++-
 net/ipv4/ipmr.c              | 69 +++++++++++++++++++++-------------
 net/ipv6/ip6mr.c             | 73 ++++++++++++++++++++++--------------
 4 files changed, 99 insertions(+), 57 deletions(-)

-- 
2.20.1