Fix double free in createExtrudedMesh, reported by ptitSeb

src/mesh.cpp

@@ -284,7 +284,6 @@ scene::IAnimatedMesh* createExtrudedMesh(video::ITexture *texture,
 		if (img2 != NULL)
 		{
 			img1->copyTo(img2);
-			img1->drop();
 
 			mesh = extrudeARGB(size.Width, size.Height, (u8*) img2->lock());
 			img2->unlock();