h8300: select generic atomic64_t support

Rationals from Eric:

So I just looked a little deeper and it appears architectures that do not support atomic64_t are broken.

The generic atomic64 support came in 2009 to support the perf subsystem with the expectation that all architectures would implement atomic64 support.

Furthermore upon inspection of the kernel atomic64_t is used in a fair number of places beyond the performance counters:

block/blk-cgroup.c
drivers/acpi/apei/
drivers/block/rbd.c
drivers/crypto/nx/nx.h
drivers/gpu/drm/radeon/radeon.h
drivers/infiniband/hw/ipath/
drivers/infiniband/hw/qib/
drivers/staging/octeon/
fs/xfs/
include/linux/perf_event.h
include/net/netfilter/nf_conntrack_acct.h
kernel/events/
kernel/trace/
net/mac80211/key.h
net/rds/

The block control group, infiniband, xfs, crypto, 802.11, netfilter. Nothing quite so fundamental as fs/namespace.c but definitely in multiplatform-code that should work, and is already broken on those architecutres.

Looking at the implementation of atomic64_add_return in lib/atomic64.c the code looks as efficient as these kinds of things get.

Which leads me to the conclusion that we need atomic64 support on all architectures.

---
 arch/h8300/Kconfig |    1 +
 1 file changed, 1 insertion(+)

@@ -6,6 +6,7 @@ config H8300
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select GENERIC_IRQ_SHOW
 	select GENERIC_CPU_DEVICES
+	select GENERIC_ATOMIC64
 
 config SYMBOL_PREFIX
 	string