fix ./build-qemu --clean

Was failing with:

```
TypeError: clean_pre() takes 1 positional argument but 2 were given
```

Author: cirosantilli

common.py

@@ -1997,7 +1997,7 @@ def _build_one(
                 )
         return ret
 
-    def clean_pre(self):
+    def clean_pre(self, build_dir):
         pass
 
     def clean(self):
@@ -2007,7 +2007,7 @@ def clean(self):
             self.sh.rmrf(build_dir)
         self.clean_post(build_dir)
 
-    def clean_post(self):
+    def clean_post(self, build_dir):
         pass
 
     def build(self):