Cleanup c programs (#1620)

Cleanup C programs

programs/bpf/rust/noop/src/lib.rs

@@ -0,0 +1,15 @@
+extern crate rbpf;
+
+use std::mem::transmute;
+
+#[no_mangle]
+#[link_section = ".text,entrypoint"] // TODO platform independent needed
+pub extern "C" fn entrypoint(_raw: *mut u8) {
+    let bpf_func_trace_printk = unsafe {
+        transmute::<u64, extern "C" fn(u64, u64, u64, u64, u64)>(
+            rbpf::helpers::BPF_TRACE_PRINTK_IDX as u64,
+        )
+    };
+
+    bpf_func_trace_printk(0, 0, 1, 2, 3);
+}