tests: Emulate multithreading environment for unit tests

The main purpose of this patch is to run unit tests on BSD family
of OSes. The root cause is `fileno` syscall which is a macro that
can be expanded to either a function call (for multi-threaded
environment) or to inline code (for single-threaded environment).
Said inline code accesses private field of file descriptor, and
this construction is impossible to mock in unit tests. Multi-
threaded environment has `fileno` as a function, which can be
mocked in unit tests.

On other OSes the patch just creates a thread which is doing nothing.
We avoid adding pre-processor conditionals since the cost is small.

Tested on
FreeBSD 13.1-RELEASE-p6 GENERIC amd64
NetBSD 9.2 (GENERIC) amd64
OpenBSD 7.2 GENERIC#7 amd64
DragonFly v6.4.0-RELEASE x86_64
Ubuntu 22.04.1 x86_64

Change-Id: I3d65c125183e60037ad07b9d54b8fffdece5a4e8
Signed-off-by: Anastasia Klimchuk <aklm@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/74157
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Peter Marheine <pmarheine@chromium.org>
Reviewed-by: Thomas Heijligen <src@posteo.de>

0 files changed, 0 insertions, 0 deletions