Various unit tests were creating temporary files unconditionally in /tmp
and were not cleaning up after themselves. Introduce a new variant of
mkstemp(3p) that respects the TMPDIR environment variable, and use it in
the offending unit tests. This allows each test run to use a dedicated
TMPDIR that can be cleaned up after the run.
Changelog-None
Signed-off-by: Matt Whitlock <c-lightning@mattwhitlock.name>
Any file in this directory which is executable and whose name only
consists of alphanumeric characters, space, '.', '-' or '_' will be
automatically loaded when lightningd starts (unless suppressed with
commandline options).