Previous attempt failed with:
modules/copy_fail_family/src/apparmor_bypass.c:23:10:
fatal error: linux/capability.h: No such file or directory
musl-gcc points at musl's libc headers, which (correctly) don't
include Linux kernel uapi (linux/netfilter/*.h, linux/capability.h,
etc.). On Ubuntu these come from the linux-libc-dev package living
at /usr/include + /usr/include/aarch64-linux-gnu.
Fix: -isystem both paths so musl-gcc can find Linux uapi without
those paths shadowing musl's own libc decls (which they would if
we used a plain -I). The Alpine x86_64 build doesn't hit this
because Alpine's linux-headers package installs into musl's own
include path.
leviathan
3e9f373751