Make clang-tidy projects compile on clang

Compiling individual repos on clang gives us an extra set of checks, and
ensures that we are coding to the c++ standard, and not to gcc
specifics.  In practice, a lot of the repos have compiled against clang
for a while, but leads to maintainers jumping in from time to time to
fix the clang build with seemingly minor changes that are better caught
at review time.

This commit causes the clang build (created as part of the tidy checks)
to actually compile, which can find issues like
https://gerrit.openbmc-project.xyz/c/openbmc/bmcweb/+/51346 that clang
finds, but gcc does not (or allows silently).

I walked through every repo I'm aware of that are relying on clang-tidy,
and made sure that they compile with clang.  bmcweb, dbus-sensors, and
entity-manager have patchsets in review to resolve the minor issues,
that should be merged before this.

sdeventplus builds with clang as-is.

Tested:
Compiled repos above against clang with the aforementioned commits, and
build passed.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I310f9aebc75fe4bc9645c4c961ca0caf8f94b4d5
1 file changed