StarRuby Patch for LibPNG 1.5 Compatibility

--- texture.c.old.txt   2012-12-23 18:47:39.000000000 -0500
+++ texture.c   2012-12-23 18:51:29.000000000 -0500
@@ -323,22 +323,30 @@
     png_set_packing(pngPtr);
   }
   if (colorType == PNG_COLOR_TYPE_GRAY && bitDepth < 8) {
-    png_set_gray_1_2_4_to_8(pngPtr);
+    png_set_expand_gray_1_2_4_to_8(pngPtr);
   }
+
+   png_colorp png_palette = NULL;
+   int num_palette = 0;
+   png_get_PLTE(pngPtr, infoPtr, &png_palette, &num_palette);
+
   png_read_update_info(pngPtr, infoPtr);
-  if (0 < infoPtr->num_palette && hasPalette) {
+  if (0 < num_palette && hasPalette) {
     texture->indexes = ALLOC_N(uint8_t, width * height);
-    const png_colorp palette = infoPtr->palette;
-    const int numTrans = infoPtr->num_trans;
+
+
+
+   int numTrans = 0;
+   png_bytep trans = NULL;
 #if PNG_LIBPNG_VER_SONUM <= 12
-    const png_bytep trans = infoPtr->trans;
+   png_get_tRNS(pngPtr,infoPtr, &trans, &numTrans, NULL);
 #else
-    const png_bytep trans = infoPtr->trans_alpha;
+   png_get_tRNS(pngPtr,infoPtr, &trans, &numTrans, NULL);
 #endif
-    texture->paletteSize = infoPtr->num_palette;
+    texture->paletteSize = num_palette;
     Color* p = texture->palette = ALLOC_N(Color, texture->paletteSize);
     for (int i = 0; i < texture->paletteSize; i++, p++) {
-      const png_colorp pngColorP = &(palette[i]);
+      const png_colorp pngColorP = &(png_palette[i]);
       p->red   = pngColorP->red;
       p->green = pngColorP->green;
       p->blue  = pngColorP->blue;