oe-selftest: Error if the user has buildhistory enabled
buildhistory interfers with various tests so error if the user has it enabled,
hence avoiding time spent running the tests only for them to fail.
For example, if there is an sstate cache and something comes from that cache,
you can get a "version went backwards" warning from buildhistory which would
then change the outcome of a test. Its safer/easier to disable it.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
