xtask: fix include paths for kernel headers bundled with libbpf

bpf/aya-bpf-bindings/include/bindings.h

@@ -1,4 +1,8 @@
 #include <linux/types.h>
+// __wsum is missing from types.h, see
+// https://elixir.bootlin.com/linux/v5.13/source/include/uapi/linux/types.h
+typedef __u32 __bitwise __wsum;
+
 #include <linux/bpf.h>
 #include <linux/ptrace.h>
 #include <sys/socket.h>

bpf/aya-bpf/src/maps/queue.rs

@@ -1,7 +1,5 @@
 use core::{marker::PhantomData, mem};
 
-use aya_bpf_cty::c_void;
-
 use crate::{
     bindings::{bpf_map_def, bpf_map_type::BPF_MAP_TYPE_QUEUE},
     helpers::{bpf_map_pop_elem, bpf_map_push_elem},

xtask/src/codegen/aya.rs

@@ -22,6 +22,14 @@ fn codegen_internal_btf_bindings(opts: &Options) -> Result<(), anyhow::Error> {
                 .unwrap()
                 .to_string_lossy()
         ))
+        .clang_arg(format!(
+            "-I{}",
+            opts.libbpf_dir
+                .join("include")
+                .canonicalize()
+                .unwrap()
+                .to_string_lossy()
+        ))
         .header(
             opts.libbpf_dir
                 .join("src/libbpf_internal.h")

xtask/src/codegen/aya_bpf_bindings.rs

@@ -21,6 +21,11 @@ pub fn codegen(opts: &Options) -> Result<(), anyhow::Error> {
     let builder = || {
         let mut bindgen = bindgen::bpf_builder()
             .header(&*dir.join("include/bindings.h").to_string_lossy())
+            .clang_args(&[
+                "-I",
+                &*opts.libbpf_dir.join("include/uapi").to_string_lossy(),
+            ])
+            .clang_args(&["-I", &*opts.libbpf_dir.join("include").to_string_lossy()])
             .clang_args(&["-I", &*opts.libbpf_dir.join("src").to_string_lossy()])
             // open aya-bpf-bindings/.../bindings.rs and look for mod
             // _bindgen, those are anonymous enums