Add C to Rust example

c-to-rust/src/lib.rs

@@ -0,0 +1,6 @@
+#![crate_type = "staticlib"]
+
+#[no_mangle]
+pub extern fn double_input(input: i32) -> i32 {
+    input * 2
+}

c-to-rust/src/main.c

@@ -0,0 +1,11 @@
+#include <stdint.h>
+#include <stdio.h>
+
+extern int32_t double_input(int32_t input);
+
+int main() {
+    int input = 4;
+    int output = double_input(input);
+    printf("%d * 2 = %d\n", input, output);
+    return 0;
+}