Updated CMakeLists so LUA is compiled with loading of dynamic libraries enabled.

- Added define "LUA_USE_LINUX" to lua, luac and lua-lib
- Added library requirement of "dl" and "readline" to lua
- Added library requirement of "dl" to lua-lib
  This fixes "make" failing with linker error :
    undefined reference to symbol 'dlclose@@GLIBC_2.2.5'
Merge pull request #809 from samibh/fix_lua_cmake_linux

Updated CMakeLists so LUA is compiled with loading of dynamic libraries enabled