add missing üarameter to DevDrawLine for X11 and HPGL

src/frontend/hpgl.c

@@ -201,8 +201,10 @@ int GL_Clear(void)
 }
 
 
-int GL_DrawLine(int x1, int y1, int x2, int y2)
+int
+GL_DrawLine(int x1, int y1, int x2, int y2, bool isgrid)
 {
+    NG_IGNORE(isgrid);
     /* note: this is not extendible to more than one graph
        => will have to give NewViewport a writeable graph XXX */
 

src/frontend/plotting/x11.c

@@ -1194,7 +1194,7 @@ linear_arc(int x0, int y0, int radius, double theta, double delta_theta)
         y1 = y2;
         x2 = x0 + (int)(radius * cos(theta + i*dphi));
         y2 = y0 + (int)(radius * sin(theta + i*dphi));
-        X11_DrawLine(x1, y1, x2, y2);
+        X11_DrawLine(x1, y1, x2, y2, FALSE);
     }
 }