payout: take the mutex that guards the in-flight list while loading it

LoadPaying appends to gPaying and increments gPayingNextId, and both are
annotated as guarded by gPayoutExecMutex. It took neither.

Nothing is racing it today: it is called from the pool startup path
before the payout thread is spawned, and the self-test calls it on one
thread. But that is a fact about its callers, not about the function,
and the annotation is what the next person to add a caller will read.
The lock is uncontended here by construction, so there is nothing to
weigh against taking it.

Property: every mutation of gPaying and gPayingNextId in this file
happens under the mutex they are documented to be guarded by.

0 files changed, 0 insertions, 0 deletions