x86_64 compiler + elf output (can compile code that returns exit code)

src/main.rs

@@ -7,6 +7,7 @@ mod parser;
 mod parser_ir;
 
 fn main() {
+    return crate::backend::test_x86_64();
     let mut args = std::env::args();
     let Some(path) = args.nth(1) else {
         println!("file expected");