make distclean before configuring an existing folder

We suppose the intent from the user when configuring an existing
directory is to rebuild all the binaries for the new configuration. For
example, the user could have changed the sysroot.

Apertis: https://phabricator.apertis.org/T3557



Signed-off-by: Frédéric Dalleau <frederic.dalleau@collabora.com>
Reviewed-by: Emanuele Aina <emanuele.aina@collabora.com>
Differential Revision: https://phabricator.apertis.org/D6141

tools/ade

@@ -913,6 +913,9 @@ class Project:
         if self.build_dir:
             subprocess.run(['mkdir', '-p', self.build_dir])
 
+        if os.path.exists(os.path.join(self.root, self.build_dir, 'Makefile')):
+            self.make('distclean')
+
         p = subprocess.Popen(args, cwd=os.path.join(self.root, self.build_dir), env=env)
         p.wait()