Remove FindSDL2 find-module, use sdl2-config.cmake instead This requires SDL >= 2.0.4. Since <https://bugzilla.libsdl.org/show_bug.cgi?id=2464> was fixed in SDL 2.0.4, SDL behaves as a CMake "config-file package", even if it was not itself built using CMake: it installs a sdl2-config.cmake file to ${libdir}/cmake/SDL2, which tells CMake where to find SDL's headers and library, analogous to a pkg-config .pc file. As a result, we no longer need to copy/paste a "find-module package" to be able to find a system copy of SDL >= 2.0.4 with find_package(SDL2). Find-module packages are now discouraged by the CMake developers, in favour of having upstream projects behave as config-file packages. This results in a small API change: FindSDL2 used to set SDL2_INCLUDE_DIR and SDL2_LIBRARY, but the standard behaviour for config-file packages is to set <name>_INCLUDE_DIRS and <name>_LIBRARIES. Use the CONFIG keyword to make sure we search in config-file package mode, and will not find a FindSDL2.cmake in some other directory that implements the old interface. In addition to deleting redundant code, this avoids some assumptions in FindSDL2 about the layout of a SDL installation. The current libsdl2-dev package in Debian breaks those assumptions; this is considered a bug and will hopefully be fixed soon, but it illustrates how fragile these assumptions can be. We can be more robust against different installation layouts by relying on SDL's own CMake integration. When linking to a copy of CMake in a non-standard location, users can now set the SDL2_DIR or CMAKE_PREFIX_PATH environment variable to point to it; previously, these users would have used the SDL2DIR environment variable. This continues to be unnecessary if using matching system-wide installations of CMake and SDL2, for example both from Debian.

# Find liblua
#
# Once done this will define
#  LUA_FOUND - system has Lua
#  LUA_INCLUDE_DIR - the Lua include directory
#  LUA_LIBRARY - The library needed to use Lua
# Copyright (c) 2013, Vittorio Giovara <vittorio.giovara@gmail.com>
#
# Distributed under the OSI-approved BSD License (the "License");
# see accompanying file Copyright.txt for details.
#
# This software is distributed WITHOUT ANY WARRANTY; without even the
# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the License for more information.

include(FindPackageHandleStandardArgs)

find_path(LUA_INCLUDE_DIR lua.h
                          PATHS /usr/include /usr/local/include /usr/pkg/include
                          PATH_SUFFIXES lua5.1 lua51 lua-5.1)
find_library(LUA_LIBRARY NAMES liblua lua51 lua5.1 lua-5.1 lua
                         PATHS /lib /usr/lib /usr/local/lib /usr/pkg/lib)

find_package_handle_standard_args(Lua DEFAULT_MSG LUA_LIBRARY LUA_INCLUDE_DIR)
mark_as_advanced(LUA_INCLUDE_DIR LUA_LIBRARY)