feat: add ffi c

__ffi/c2/cfunctions.c

@@ -0,0 +1,15 @@
+#include "cfunctions.h"
+#include "stdio.h"
+#include <stdlib.h>
+
+void doit(int nr) {
+  printf("Do something. nr: %d\n", nr);
+  printf("Going to call exit\n");
+  exit(1);
+  printf("After calling exit\n");
+}
+
+void print_string(char* s) {
+  printf("print_string. s: %s\n", s);
+}
+