Some older compilers do not support overflow builtins introduced in
5ad2aacd24 ("btrfs-progs: kernel-lib: sync include/overflow.h"). Add
stubs to make it compile. This fixes CI build of Centos 7.
Signed-off-by: David Sterba <dsterba@suse.com>
Copy of include/linux/overflow.h from the kernel.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
[ split from the original patch ]
Signed-off-by: David Sterba <dsterba@suse.com>
