[flashrom-gerrit] Change in flashrom[master]: flashrom.c: Implement file-based locking semantics

[Daniel Campello (Code Review)]

Attention is currently required from: Hung-Te Lin, Nico Huber, Subrata Banik, Edward O'Callaghan.
Daniel Campello has uploaded a new patch set (#14) to the change originally created by Edward O'Callaghan. ( https://review.coreboot.org/c/flashrom/+/62213 )

Change subject: flashrom.c: Implement file-based locking semantics
......................................................................

flashrom.c: Implement file-based locking semantics

This upstreams the ChromiumOS implementation of file-based locking
for multiple instances of flashrom that could be spawned either
from libflashrom (perhaps by fwupd for example) and user cli
as another example. Since flashrom is programming singleton state
of hardware from userspace there is no way to exclusively own
the address space and therefore a file-based locking semantic
is considered here.

BUG=b:217629892,b:215255210
BRANCH=none
TEST=nm -gD /build/brya/usr/lib64/libflashrom.so | grep "flock"
     Test futility update with multiple instances of flashrom running.

Change-Id: I19cb4e3bf14caeb67c3e8100a20395b264c5113a
Signed-off-by: Edward O'Callaghan 
---
M Makefile
A big_lock.c
A big_lock.h
A file_lock.c
M flashrom.c
A ipc_lock.h
M meson.build
M tests/chip.c
M tests/include/test.h
M tests/io_mock.h
M tests/lifecycle.c
11 files changed, 462 insertions(+), 12 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/13/62213/14