Started preparing Bochs for SDL2 support. Set up GUI_LINK_OPTS_SDL in the
configure script (SDL2 uses 'sdl2-config' instead of 'sdl-config').


git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@12382 6c8e4198-a580-4521-a02f-c9ae86df1db9