Make package.path and package.cpath unique in win32 bin scripts.

[xpol]

It happens that I manually installed Lua and LuaRocks in the follow structure:

{ROOT}
|   config.lua
|   lua.exe
|   lua53.dll
|   lua53.lib
|   luacheck.bat
|   luarocks
|   luarocks.bat
|
+---cmod
|       lfs.dll
|
+---doc
|
+---include
|       lauxlib.h
|       lua.h
|       lua.hpp
|       luaconf.h
|       lualib.h
|
+---lua
|   +---luacheck
|   |       analyze.lua
|   |       ...
|   |       version.lua
|   |
|   \---luarocks
|       |   add.lua
|       |   ...
|       |   write_rockspec.lua
|       |
|       +---build
|       |       builtin.lua
|       |       cmake.lua
|       |       command.lua
|       |       make.lua
|       |
|       +---fetch
|       |       cvs.lua
|       |       ...
|       |       svn.lua
|       |
|       +---fs
|       |   |   lua.lua
|       |   |   unix.lua
|       |   |   win32.lua
|       |   |
|       |   +---unix
|       |   |       tools.lua
|       |   |
|       |   \---win32
|       |           tools.lua
|       |
|       +---tools
|       |       patch.lua
|       |       tar.lua
|       |       zip.lua
|       |
|       \---upload
|               api.lua
|               multipart.lua
|
+---rocks
|   |   manifest
|   |
|   +---luacheck
|   |   \---0.15.1-1
|   |       |   luacheck-0.15.1-1.rockspec
|   |       |   rock_manifest
|   |       |
|   |       +---bin
|   |       |       luacheck
|   |       |
|   |       +---doc
|   |       \---lua
|   \---luafilesystem
|       \---1.6.3-2
|           |   luafilesystem-1.6.3-2.rockspec
|           |   rock_manifest
|           |
|           +---doc
|           \---tests
|
\---tools
        7z.exe
        ...
        wget.exe

in config.lua:

rocks_trees = {
  {
    root="{ROOT}",
    bin_dir="{ROOT}",
    lib_dir="{ROOT}/cmod",
    lua_dir="{ROOT}/lua"
  }
}

in site_config.lua:

site_config.LUAROCKS_PREFIX=[[{ROOT}]]

• The extra_luarocks_module_dir (site_config.LUAROCKS_PREFIX..'lua/?.lua' == {ROOT}/lua/?.lua)
• And rocks_trees.lua_dir .. '/?.lua' == {ROOT}/lua/?.lua

That is in this case of configuration. extra_luarocks_module_dir is duplicated with lua directory for the tree.

So I:

1. add 2 lines in src/luarocks/fs/win32.lua to remove duplicated path in lpath and lcpath.
2. use / instead of \\ in extra_luarocks_module_dir.

[hishamhm]

Patch looks fine, thanks! :)