configure: Disable the address sanitizer

The autoconf test passes even if the library is missing meaning that
the application compiles but will not link.

Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>
tests: empty and flags tests

Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>
Pre-pre-process local include files.

Addresses the following comment from the known bugs:
> * Local headers (those included using double quotes and checked for
>   related source files, see Include file handling, above) are not
>   currently pre-pre-processed to detect other related source files.

Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>
tests: Make the logs for the self-hosting test more useful

Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>