feat: add ffi c

__ffi/c2/something.rs

@@ -0,0 +1,19 @@
+use std::ffi::CString;
+use std::os::raw::c_char;
+
+// The below can be left out if the library is specified to 
+// rustc as an option.
+//#[link(name = "cfunctions", kind="dylib")]
+extern "C" {
+  fn doit(nr: i32) -> ();
+  fn print_string(s: *const c_char) -> ();
+}
+
+fn main() {
+  println!("Example of calling a c library.");
+  let s = CString::new("bajja").expect("CString::new failed");
+  unsafe {
+    doit(18);
+    print_string(s.as_ptr());
+  }
+}