video: explicitly check for aspect_ratio_correct's value being 1

This doesn't make any factual change for Choco but allows forks to
assign different values to this variable.

src/i_video.c

@@ -1356,7 +1356,7 @@ void I_InitGraphics(void)
         fullscreen = true;
     }
 
-    if (aspect_ratio_correct)
+    if (aspect_ratio_correct == 1)
     {
         actualheight = SCREENHEIGHT_4_3;
     }

src/setup/display.c

@@ -144,7 +144,7 @@ static void GenerateSizesTable(TXT_UNCAST_ARG(widget),
     int i;
 
     // Pick which window sizes list to use
-    if (aspect_ratio_correct)
+    if (aspect_ratio_correct == 1)
     {
         sizes = window_sizes_scaled;
     }

src/v_video.c

@@ -737,7 +737,7 @@ void WritePNGfile(char *filename, pixel_t *data,
     int w_factor, h_factor;
     byte *rowbuf;
 
-    if (aspect_ratio_correct)
+    if (aspect_ratio_correct == 1)
     {
         // scale up to accommodate aspect ratio correction
         w_factor = 5;