fix pyabc to link correctly on some linux version, fixing problem caused by the…

fix pyabc to link correctly on some linux version, fixing problem caused by the changeset named: Suggested changes to counting time in Abc_Clock()

src/python/setup.py

@@ -30,6 +30,7 @@ else:
         define_macros.append( ('LIN', 1) )
 
     libraries.append( 'abc' )
+    libraries.append( 'rt' )
     libraries.append( 'readline' )
     library_dirs.append('./../../')