[librptexture] Qoi: qoi.h has the R and B channels swapped compared to what rp_image expects.

This was broken since support for Qoi was added in v2.5. Not sure why
I didn't notice it until now...

Affects: v2.4 - v2.5

NEWS.md

@@ -33,6 +33,8 @@
     empty data as a PNG image. (Needs more debugging for a proper fix...)
     * See #451: libpng errors crash due to libpng setjmp/longjmp (Windows 10, release builds only)
       * Reported by @Masamune3210.
+  * Qoi: R/B channels were incorrectly swapped when this was first added in v2.5.
+    * Affects: v2.5 - v2.5.1
 
 * Other changes:
   * rpcli: Added more colorization for warning messages.

src/librptexture/fileformat/Qoi.cpp

@@ -162,7 +162,14 @@ rp_image_const_ptr QoiPrivate::loadImage(void)
 		px_src += src_stride;
 	}
 	free(pixels);
-	
+
+	// NOTE: qoi.h has the R and B channels swapped compared to what rp_image expects.
+	int ret = tmp_img->swizzle("bgra");
+	if (ret != 0) {
+		// Swizzle failed.
+		return {};
+	}
+
 	img.reset(tmp_img);
 	return img;
 }