Don't emit _start entry point in test mode

Author: phil-opp

src/lib.rs

@@ -14,6 +14,7 @@ pub mod bootinfo;
 #[macro_export]
 macro_rules! entry_point {
     ($path:path) => {
+        #[cfg(not(test))]
         #[export_name = "_start"]
         pub extern "C" fn __impl_start(boot_info: &'static $crate::bootinfo::BootInfo) -> ! {
             // validate the signature of the program entry point