integration-test: properly rebuild bpf on change

test/integration-test/build.rs

@@ -96,6 +96,7 @@ fn main() {
 
         for (src, dst) in c_bpf_probes {
             let src = bpf_dir.join(src);
+            println!("cargo:rerun-if-changed={}", src.to_str().unwrap());
             let mut cmd = Command::new("clang");
             cmd.arg("-I")
                 .arg(&libbpf_headers_dir)
@@ -117,6 +118,7 @@ fn main() {
         }
 
         let ebpf_dir = manifest_dir.parent().unwrap().join("integration-ebpf");
+        println!("cargo:rerun-if-changed={}", ebpf_dir.to_str().unwrap());
         let target = format!("{target}-unknown-none");
 
         let mut cmd = Command::new("cargo");