Make the configure script look for SDL2

platform/unix/configure.ac

@@ -18,7 +18,7 @@ includes=
 
 # Libraries
 AC_SEARCH_LIBS([sqrt], [m], [], AC_MSG_ERROR([Can't LÖVE without C math library]))
-AC_SEARCH_LIBS([SDL_Init], [SDL], [], AC_MSG_ERROR([Can't LÖVE without SDL]))
+AC_SEARCH_LIBS([SDL_Init], [SDL2], [], AC_MSG_ERROR([Can't LÖVE without SDL 2]))
 AC_SEARCH_LIBS([glLoadIdentity], [GL], [], AC_MSG_ERROR([Can't LÖVE without OpenGL]))
 AC_SEARCH_LIBS([alSourcePlay], [openal], [], AC_MSG_ERROR([Can't LÖVE without OpenAL]))
 AC_SEARCH_LIBS([ilInit], [IL], [], AC_MSG_ERROR([Can't LÖVE without DevIL]))
@@ -28,7 +28,7 @@ AC_SEARCH_LIBS([ModPlug_Load], [modplug], [], AC_MSG_ERROR([Can't LÖVE without
 AC_SEARCH_LIBS([ov_open], [vorbisfile], [], AC_MSG_ERROR([Can't LÖVE without VorbisFile]))
 
 # Includes
-AC_CHECK_HEADER([SDL/SDL.h], [includes="$includes -I/usr/include/SDL"])
+AC_CHECK_HEADER([SDL2/SDL.h], [includes="$includes -I/usr/include/SDL2"])
 AC_CHECK_HEADER([freetype2/freetype/config/ftheader.h], [includes="$includes -I/usr/include/freetype2"])
 
 # Lua, treated seperately because of --with-lua