It's not very good, but it supports all of the options by the
previous far-worse Makefile configure targets, and also now supports
out-of-tree builds.
Also include the relevent updates to the .buildbot script and
.gitignore.
Using lcov, generate an HTML report via "make coverage-report"
describing the coverage of each file. Ideally, this will get added to
an automated testing pipeline.
Signed-off-by: Max Regan <mgregan2@gmail.com>
