Ensure stable file prefixes in the *_gnu import libraries

For some reason, the import libraries currently in the repository don't
match what running the tool_gnu command produces, due to the use of
different prefixes. This adjusts the command to produce the same
prefixes as the ones currently in the import libraries from the
repository.

crates/tools/gnu/src/main.rs

@@ -82,6 +82,13 @@ EXPORTS
     cmd.arg(format!("{}.def", library));
     cmd.arg("-l");
     cmd.arg(format!("lib{}.a", library));
+    // Ensure consistency in the prefixes used by dlltool.
+    cmd.arg("-t");
+    if library.contains('.') {
+        cmd.arg(format!("{}_", library).replace('.', "_").replace('-', "_"));
+    } else {
+        cmd.arg(format!("{}_dll_", library).replace('-', "_"));
+    }
     cmd.output().unwrap();
 
     // Work around lack of determinism in dlltool output.