Auto merge of rust-lang#106092 - asquared31415:start_lang_item_checks, r=davidtwco

Add checks for the signature of the `start` lang item

Closes rust-lang#105963

Author: bors

tests/ui/def_id_nocore.rs

@@ -15,7 +15,7 @@ pub trait Copy {}
 pub unsafe trait Freeze {}
 
 #[lang = "start"]
-fn start<T>(_main: fn() -> T, _argc: isize, _argv: *const *const u8) -> isize {
+fn start<T>(_main: fn() -> T, _argc: isize, _argv: *const *const u8, _sigpipe: u8) -> isize {
     0
 }