thread: add qemu_spin_destroy

It will be used for TSAN annotations.

Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Robert Foley <robert.foley@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200609200738.445-4-robert.foley@linaro.org>
Message-Id: <20200612190237.30436-7-alex.bennee@linaro.org>

include/qemu/thread.h

@@ -215,6 +215,9 @@ static inline void qemu_spin_init(QemuSpin *spin)
     __sync_lock_release(&spin->value);
 }
 
+static inline void qemu_spin_destroy(QemuSpin *spin)
+{ }
+
 static inline void qemu_spin_lock(QemuSpin *spin)
 {
     while (unlikely(__sync_lock_test_and_set(&spin->value, true))) {