fix clang warnings

src/bigrationalR.cc

@@ -127,7 +127,7 @@ namespace bigrationalR
     if (TYPEOF(denAttr) != NILSXP)
       {
 	bigvec_q attrib = bigrationalR::create_vector(denAttr);
-	if (!attrib.size() == 0) // sanity check
+	if (attrib.size() != 0) // sanity check
 	  for (unsigned int i = 0; i < v.size(); ++i)
 	    {
 	      if( attrib[i%attrib.size()].sgn() != 0)