Add a post-dist test for compiling a basic program with Cranelift

Author: Kobzol

tests/ui/dist/cranelift-x86_64-unknown-linux-gnu-dist.rs

@@ -0,0 +1,10 @@
+// Ensure that Cranelift can be used to compile a simple program with `x86_64-unknown-linux-gnu`
+// dist artifacts.
+
+//@ only-dist
+//@ only-x86_64-unknown-linux-gnu
+//@ compile-flags: -Z codegen-backend=cranelift
+
+fn main() {
+    println!("Hello world!");
+}