LuaJIT Unicode for Windows

This is an adaptation of https://github.com/Lekensteyn/lua-unicode to work under LuaJIT and for the purpose of Pragtical Code Editor.

Changes

1. Copy src/utf8_wrappers.h and src/utf8_wrappers.c to LuaJIT src dir.
2. Patch src/luaconf.h to add the following in the Local configuration part:

#if defined(LUA_LIB) && (defined(lib_aux_c) || defined(lib_io_c) || \
     defined(lib_package_c) || defined(lib_os_c))
#include "utf8_wrappers.h"
#endif

3. Patch src/Makefile to compile src/utf8_wrappers.c:

-	 lib_buffer.o
+	 lib_buffer.o utf8_wrappers.o