CONFIG_DEBUG_SPINLOCK only adds spinlock tests for SMP builds. The
attached patch adds runtime checks for uniprocessor builds.

Tested on i386/UP, but it should work on all platforms. It contains
runtime checks for:

- missing initialization
- recursive lock
- double unlock
- incorrect use of spin_is_locked() or spin_trylock() [both function
do not work as expected on uniprocessor builds]
The next step are checks for spinlock ordering mismatches.

Which other runtime checks are possible?
Tests for correct _irq usage are not possible, several drivers use
disable_irq().

--
	Manfred