lib: replace SDL usage to Boost one

It is safer and header-only, and can be removed after C++23 is accepted.
There is no need for SDL in non-GUI.

lib/filesystem/CBinaryReader.cpp

@@ -10,14 +10,12 @@
 #include "StdInc.h"
 #include "CBinaryReader.h"
 
-//FIXME:library file depends on SDL - make cause troubles
-#include <SDL_endian.h>
 #include "CInputStream.h"
 #include "../CGeneralTextHandler.h"
 
 VCMI_LIB_NAMESPACE_BEGIN
 
-#if SDL_BYTEORDER == SDL_BIG_ENDIAN
+#ifdef VCMI_ENDIAN_BIG
 template <typename CData>
 CData readLE(CData data)
 {