This is difficult because security/selinux/ doesn't use the *actual* kernel headers for the kernel being built to get the AF_MAX/PF_MAX defines; those are not included in the kernel uapi headers. Instead, those defines come from /usr/include/x86_64-linux-gnu/bits/socket.h which is provided by:
$ dpkg -S bits/socket.h
libc6-dev:amd64: /usr/include/x86_64-linux-gnu/bits/socket.h
This is difficult because security/selinux/ doesn't use the *actual* kernel headers for the kernel being built to get the AF_MAX/PF_MAX defines; those are not included in the kernel uapi headers. Instead, those defines come from /usr/include/ x86_64- linux-gnu/ bits/socket. h which is provided by: x86_64- linux-gnu/ bits/socket. h
$ dpkg -S bits/socket.h
libc6-dev:amd64: /usr/include/