Add IPsec tunnel mode feature flag

This patch adds a feature flag for IPsec Tunnel Mode. This implies VTI
(with output-mark updating), or XFRM-I in the kernels.

Bug: 117183273
Test: Compiles
Change-Id: I9c1a84707366c841c27b74050d276cac9bd61460
Merged-In: I9c1a84707366c841c27b74050d276cac9bd61460
(cherry picked from commit 6300d068380d5b7bea498bfd0c86a841ebcb2034)
1 file changed