[PATCH] block: blk-iocost: fix build for ARCH with missing local64.h files

[Randy Dunlap <rdunlap@infradead.org>]

When building block/blk-iocost.c on arch/x6x/ or arch/nios2/, the
build fails due to missing the <asm/local64.h> file.

Fix this by adding local64.h as a "generic-y" file in their respective
Kbuild files, so that they will use a copy of <asm-generic/local64.h>
instead (copied to arch/*/include/generated/local64.h by the
build system).

c6x or nios2 build error:
../block/blk-iocost.c:183:10: fatal error: asm/local64.h: No such file or directory
  183 | #include <asm/local64.h>

Fixes: 5e124f74325d ("blk-iocost: use local[64]_t for percpu stat")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Aurelien Jacquiot <jacquiot.aurelien@gmail.com>
Cc: linux-c6x-dev@linux-c6x.org
---
 arch/c6x/include/asm/Kbuild   |    1 +
 arch/nios2/include/asm/Kbuild |    1 +
 2 files changed, 2 insertions(+)

--- linux-next-20201208.orig/arch/c6x/include/asm/Kbuild
+++ linux-next-20201208/arch/c6x/include/asm/Kbuild
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 generic-y += extable.h
 generic-y += kvm_para.h
+generic-y += local64.h
 generic-y += mcs_spinlock.h
 generic-y += user.h
--- linux-next-20201208.orig/arch/nios2/include/asm/Kbuild
+++ linux-next-20201208/arch/nios2/include/asm/Kbuild
@@ -2,6 +2,7 @@
 generic-y += cmpxchg.h
 generic-y += extable.h
 generic-y += kvm_para.h
+generic-y += local64.h
 generic-y += mcs_spinlock.h
 generic-y += spinlock.h
 generic-y += user.h