Split tests into primitives

This ensures separate errors for separate common files

test/test_common.py

@@ -12,6 +12,10 @@ import helpers
 def test_common():
     for d in os.listdir('common'):
         primitive = re.sub(r"\.c$", "", d)
+        yield check_common, primitive
+
+
+def check_common(primitive):
     binname = os.path.join('..', 'bin', 'test_'+primitive)
     helpers.make(binname)
     helpers.run_subprocess([binname])