Fix: Update kmem event for Ubuntu's 3.16 kernel

The upstream patch in question in commit 72906e1 was cherry-picked into
Ubuntu's 3.16 kernel backport branch (called lts-utopic). The version
check should also include this branch.

The other backport branch, lts-vivid, and all following ones will be
covered by the standard

  LINUX_VERSION_CODE >= KERNEL_VERSION(3,19,2)

check, so should not require other workarounds.

References #889.

Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>