bugfix257 Reinitialize linter for each file.

- I've called this Option3 in the comments of dalance#257.
- Clone of `config` might be avoided, but this is the lowest-effort change.

src/main.rs

@@ -200,11 +200,6 @@ pub fn run_opt_config(printer: &mut Printer, opt: &Opt, config: Config) -> Resul
         not_obsolete = false;
     }
 
-    let mut linter = Linter::new(config);
-    for plugin in &opt.plugins {
-        linter.load(&plugin)?;
-    }
-
     let mut defines = HashMap::new();
     for define in &opt.defines {
         let mut define = define.splitn(2, '=');
@@ -251,6 +246,12 @@ pub fn run_opt_config(printer: &mut Printer, opt: &Opt, config: Config) -> Resul
     let mut all_pass = true;
 
     for path in &files {
+
+        let mut linter = Linter::new(config.clone());
+        for plugin in &opt.plugins {
+            linter.load(&plugin)?;
+        }
+
         let mut pass = true;
         if opt.preprocess_only {
             match preprocess(&path, &defines, &includes, false, opt.ignore_include) {