MINOR: list: fixing typo in MT_LIST_LOCK_ELT

A minor typo was made in MT_LIST_LOCK_ELT, preventing
haproxy from compiling if MT_LIST_LOCK_ELT is
used in the code.

Today, the macro is unused, and that's the reason why
the typo has remained unnoticed for such a long time.

Fixing it so it can be used in upcoming developments.

No backport required.
1 file changed