check_patch: Compile dependency before full tree check

Make sure we've got the protobuf compiler, and then
always run a build of the protobuf module (this
module is important for some internal code inside tko,
but it is auto generated). If the package is lacking,
let the user know upfront. Point to the right docs
that will help to install all the needed packages.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
utils/check_patch.py: Make script to return failure on check errors

In order to have the checker script to be useful as an
automated test tool, make it return errors when *any*
of the checks return a proper exit code. This wasn't
done before because it took a long time to curate and
check full pylint results (even filtered) and fix
false negatives.

Now hopefully we'll catch more easily silly syntax
errors and py 2.4 non compliances in the autotest
tree.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
base_utils: properly search for possible site_tests src locations

The original version of this logic (0a0f49e9) looked for src dirs in
site-tests when every reference I have found uses site_tests (w/ an
underscore).

Additionally it seems the current default location for site_tests is
base_autotest + "/tmp/site_tests" as per what I found when triaging
the current client/tests/iosched_bugs make failure so add a "tmp" based
version to the search path as well.

Signed-off-by: Daniel DeFolo <daniel.defolo@hp.com>