Ported all tests to use the new cstring literal syntax.

Author: FractalFir

test/common.rs

@@ -248,7 +248,7 @@ fn println(msg: &str) {
         tmp_slice[..msg.len()].clone_from_slice(msg.as_bytes());
         tmp_slice[msg.len()] = b'\0';
         printf(
-            "%s\n\0".as_ptr() as *const i8,
+            c"%s\n".as_ptr() as *const i8,
             tmp_slice.as_ptr() as *const i8,
         );
         free(tmp as *mut core::ffi::c_void);