validate --skip and --exclude paths

Signed-off-by: onur-ozkan <work@onurozkan.dev>

Author: onur-ozkan

Diff for: src/bootstrap/src/core/config/config.rs

@@ -1314,7 +1314,20 @@ impl Config {
 
         // Set flags.
         config.paths = std::mem::take(&mut flags.paths);
-        config.skip = flags.skip.into_iter().chain(flags.exclude).collect();
+        config.skip = flags
+            .skip
+            .into_iter()
+            .chain(flags.exclude)
+            .map(|p| {
+                config
+                    .src
+                    .join(&p)
+                    .canonicalize()
+                    .map_err(|e| format!("path::canonicalize failed on '{}', {e}", p.display()))
+                    .unwrap()
+            })
+            .collect();
+
         config.include_default_paths = flags.include_default_paths;
         config.rustc_error_format = flags.rustc_error_format;
         config.json_output = flags.json_output;