linux-odroid-n2-headers missing files

[karog]

When I try to install wireguard-dkms, I get build errors for building the module because of missing files, namely:
$this->bbcode_second_pass_code('', '
build/arch/arm/include/asm/opcodes.h
build/arch/arm/include/asm/xen/hypervisor.h
build/drivers/amlogic/debug/irqflags_debug_arm64.h
')
I was able to find these specific files at https://github.com/hardkernel/linux/tree/odroidn2-4.9.y which is the URL for the package linux-odroid-n2-headers. There would appear to be a lot of other missing files as well in the alarm package.

What is the best way to get this package brought up to date?