tests: test more cases for misc-memcpy.so

Vlad had recently hypothesized that we may be lagging behind of redis because
the memcpy addresses for redis are usually misaligned, both relative to the
CPU word size, and to itself.

I am adding tests for those cases in misc-memcpy.so

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
tests: gtod

I have seen gettimeofday - and the pvclock functions in general - show up
quite heavily in some profiles (some 4 - 5 %).

Although this is of course normal an expected for a system that is doing a lot
of time operations, I wanted to make sure that we are not going anything too
wasteful in there.

I wrote this simple benchmark to attest that, since we seem to have none so
far. The good news is that we are quite faster than a CentOS guest, albeit
2 x slower than the host (hard to avoid that).

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>