Fix bug in get_git_modified_files

It was ignoring files without extension.

Author: Kobzol

src/build_helper/src/git.rs

@@ -186,7 +186,10 @@ pub fn get_git_modified_files(
             let (status, name) = f.trim().split_once(char::is_whitespace).unwrap();
             if status == "D" {
                 None
-            } else if Path::new(name).extension().map_or(false, |ext| {
+            } else if Path::new(name).extension().map_or(extensions.is_empty(), |ext| {
+                // If there is no extension, we allow the path if `extensions` is empty
+                // If there is an extension, we allow it if `extension` is empty or it contains the
+                // extension.
                 extensions.is_empty() || extensions.contains(&ext.to_str().unwrap())
             }) {
                 Some(name.to_owned())