fix wipe effect skipping frames when rendering takes "too long"

software mode at high resolutions takes longer to render and to dump frames than opengl at comparable resolutions. so more real time passes between frames, which makes the ending advance the melt effect further than normal on the next frame.

the code was always doing this, but it was written with much lower resolution in mind too, and viddump wasn't as widespread back then maybe?

now melt consistently takes 45 frames, even tho in `wipe_doMelt()` cph says it takes 25 for some reason (that whole comment kinda contradicts current reality anyway).

fixes #714

Author: vadosnaprimer

prboom2/src/f_wipe.c

@@ -127,25 +127,25 @@ static int wipe_doMelt(int ticks)
         if (y_lookup[i]+dy >= SCREENHEIGHT)
           dy = SCREENHEIGHT - y_lookup[i];
 
-       if (V_IsSoftwareMode()) {
-        s = wipe_scr_end.data    + (y_lookup[i]*wipe_scr_end.pitch+i);
-        d = wipe_scr.data        + (y_lookup[i]*wipe_scr.pitch+i);
-        for (j=dy;j;j--) {
-          d[0] = s[0];
-          d += wipe_scr.pitch;
-          s += wipe_scr_end.pitch;
+        if (V_IsSoftwareMode()) {
+          s = wipe_scr_end.data    + (y_lookup[i]*wipe_scr_end.pitch+i);
+          d = wipe_scr.data        + (y_lookup[i]*wipe_scr.pitch+i);
+          for (j=dy;j;j--) {
+            d[0] = s[0];
+            d += wipe_scr.pitch;
+            s += wipe_scr_end.pitch;
+          }
         }
-       }
         y_lookup[i] += dy;
-       if (V_IsSoftwareMode()) {
-        s = wipe_scr_start.data  + i;
-        d = wipe_scr.data        + (y_lookup[i]*wipe_scr.pitch+i);
-        for (j=SCREENHEIGHT-y_lookup[i];j;j--) {
-          d[0] = s[0];
-          d += wipe_scr.pitch;
-          s += wipe_scr_end.pitch;
+        if (V_IsSoftwareMode()) {
+          s = wipe_scr_start.data  + i;
+          d = wipe_scr.data        + (y_lookup[i]*wipe_scr.pitch+i);
+          for (j=SCREENHEIGHT-y_lookup[i];j;j--) {
+            d[0] = s[0];
+            d += wipe_scr.pitch;
+            s += wipe_scr_end.pitch;
+          }
         }
-       }
         done = false;
       }
     }