Use platform independent types

Author: oli-obk

src/test/ui/issues/issue-54410.rs

@@ -1,6 +1,5 @@
-use std::os::raw::c_char;
 extern "C" {
-    pub static mut symbol: [c_char];
+    pub static mut symbol: [i8];
     //~^ ERROR the size for values of type `[i8]` cannot be known at compilation time
 }
 

src/test/ui/issues/issue-54410.stderr

@@ -1,8 +1,8 @@
 error[E0277]: the size for values of type `[i8]` cannot be known at compilation time
-  --> $DIR/issue-54410.rs:3:28
+  --> $DIR/issue-54410.rs:2:28
    |
-LL |     pub static mut symbol: [c_char];
-   |                            ^^^^^^^^ doesn't have a size known at compile-time
+LL |     pub static mut symbol: [i8];
+   |                            ^^^^ doesn't have a size known at compile-time
    |
    = help: the trait `std::marker::Sized` is not implemented for `[i8]`
    = note: to learn more, visit <https://doc.rust-lang.org/book/second-edition/ch19-04-advanced-types.html#dynamically-sized-types-and-the-sized-trait>