[Xenial SRU] Fix modprobe of test_bpf

[Stefan Bader]

[SRU Justification]

Impact: One of the self-tests which is run by test_bpf will always fail
when JIT is turned on, causing the module load to fail.

Fix: Picking two patches from upstream will fix this.

Testcase: sudo modprobe test_bpf

Risk of regression: Minimal, this modifies only a test module, no impact
on normal operation.

Note about Artful: right now there is no change to introduce
CONFIG_BPF_JIT_ALWAYS_ON. But I beleive it was something considered
to be security relevant. Which means those two patches might become
relevant at some time.

-Stefan