linux-2.4.9: atomic_dec_and_lock sometimes used while not defined

["Adam J. Richter" <adam@yggdrasil.com>]

	If I try to build a kernel that can do SMP and run on a 386,
the linux-2.4.9 NFS client gets compiled with an undefined reference
to atomic_dec_and_lock().  I imagine that the correct fix is to
change the ifdefs that bracket the following line in include/linux/spinlock.h:

#define atomic_dec_and_lock(atomic,lock) atomic_dec_and_test(atomic)

	However, I'm really not clear enough on the semantics of
atomic_dec_and_lock vs. atomic_dec_and_test to know whether this
is safe.

	Also, it looks like arch/sparc64/sparc64_ksyms.c references
atomic_dec_and_test without it every being defined on any architecture
other than x86, so I am suspicious of a partially applied patch here.

	If nobody has a better idea, I'm going to move the
#define statement that I mentioned above out of its current
ifdef logic and just bracket it like so:

#ifndef CONFIG_HAVE_DEC_LOCK
#define atomic_dec_and_lock(atomic,lock) atomic_dec_and_test(atomic)
#endif

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