perf tools: Add missing headers in perf's MANIFEST

These lost headers are found in arm64 cross buildings, failing to build
perf using tarballs generated using:

 $ make perf-targz-src-pkg
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1452263041-225488-3-git-send-email-wangnan0@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/MANIFEST

 tools/perf
 tools/arch/alpha/include/asm/barrier.h
 tools/arch/arm/include/asm/barrier.h
+tools/arch/arm64/include/asm/barrier.h
 tools/arch/ia64/include/asm/barrier.h
 tools/arch/mips/include/asm/barrier.h
 tools/arch/powerpc/include/asm/barrier.h
@@ -30,6 +31,7 @@ tools/lib/find_bit.c
 tools/include/asm/atomic.h
 tools/include/asm/barrier.h
 tools/include/asm/bug.h
+tools/include/asm-generic/atomic-gcc.h
 tools/include/asm-generic/barrier.h
 tools/include/asm-generic/bitops/arch_hweight.h
 tools/include/asm-generic/bitops/atomic.h