small potential valgrind issue

bgn2/src/Curvepoint.cpp

@@ -375,7 +375,7 @@ size_t CurvepointHash::operator()(const Curvepoint& x) const
         return 0;
     }
 
-    size_t retval;
+    size_t retval = 0;
     std::hash<double> hasher;
 
     Curvepoint affine_x = x;
@@ -397,7 +397,7 @@ size_t TwistpointHash::operator()(const Twistpoint& x) const
         return 0;
     }
 
-    size_t retval;
+    size_t retval = 0;
     std::hash<double> hasher;
 
     Twistpoint affine_x = x;