Get miri working again after the #[start] attribute was removed

Just followed the suggestions from the compiler after removing the
feature flag, seems to be failing for a sensible reason (can't call
`furi_record_open`).

rust-lang/rust#134299

Author: loftyinclination

crates/flipperzero/src/lib.rs

@@ -5,8 +5,7 @@
 //!
 
 #![no_std]
-#![cfg_attr(all(test, not(miri)), no_main)]
-#![cfg_attr(all(test, miri), feature(start))]
+#![cfg_attr(test, no_main)]
 #![cfg_attr(docsrs, feature(doc_cfg))]
 #![deny(rustdoc::broken_intra_doc_links)]
 #![warn(clippy::undocumented_unsafe_blocks)]

crates/test/macros/src/lib.rs

@@ -142,8 +142,8 @@ fn tests_runner_impl(args: TokenStream) -> parse::Result<TokenStream> {
         }
 
         #[cfg(all(test, miri))]
-        #[start]
-        fn main(argc: isize, argv: *const *const u8) -> isize {
+        #[unsafe(no_mangle)]
+        fn miri_start(argc: isize, argv: *const *const u8) -> isize {
             // TODO: Is there any benefit to Miri in hooking up the binary arguments to
             // the test runner?
             let ret = __test_runner::main(None);