The `struct k_spinlock` size is zero bytes under certain
circumstances. This is a bit of a problem, because it breaks a
number of assumptions about things in C.
That should be fixed when #59922 is addressed.
This change is just a hotfix to correct the specific condition
where we will need workarounds in other source files.
Signed-off-by: Christopher Friedt <cfriedt@meta.com>
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