Update framebuffer & blitbuffer handling

Pull in current code from KoReader. This should fix Kobo display
handling, which was buggy.
remove old SDL interface (now SDL1/SDL2)
update LuaJIT, switch to 2.1 (beta) branch
fix wrong check for cross-compilation

ARCH is in any case set at this point, so check for CROSS instead.
create dummy rfbconfig.h for libvncviewer compilation
.gitignore for this project
use non-debug version of blitbuffer.lua, add shebang
Revert "Update framebuffer & blitbuffer handling"

This reverts commit 69ba3be2bc8aacbfacbc93470953231ae8920296.

will need finer grained changes since there are conflicts in the input
layer which is entangled with the SDL framebuffer handling
remove blitbuffer debug layer
update blitbuffer API to current Koreader version
add current linux framebuffer API from Koreader
Revert "remove old SDL interface (now SDL1/SDL2)"

This reverts commit 72573a4d4b89269292c83df176738844a030acd1.
Restores framebuffer implementation for SDL interface.
add BGR32 blitbuffer implementation

VNC uses BGR32 by default
update submodules libvncserver and zlib