make clean before building sda

fixes #37 (closed)

packages/sda/package.py

@@ -50,6 +50,11 @@ class Sda(MakefilePackage):
         install_tree('examples', prefix.examples)
         install_tree('lib', prefix.lib)
 
+    @run_before('build')
+    def make_clean(self):
+        with working_dir('src'):
+            make("clean")
+
     @run_after('install')
     def test_install(self):
         # run random test