macosx x86_64

Mac OS X port is done.

Thanks to Stewart Greenhill for the access to the mac machine.

* for that clang backend was prepared.
* many clang warnings were silenced. (not all though) (:
* X11 bindings don’t work, cause there is no X11 on Mac OS X out of the box.
* static linking to libSystem is not possible, due to the fact that Apple does not provide .a archive files for static linking.
* both dynamic and static linking to libVishapOberon works.

Fun fact. Usually, when I get a voc binary, I try to recompile voc with the new voc, and check for md5 sums. They should be the same, voc should produce an exact copy of itself. If it’s not, then most probably next time it won’t be able to compile itself. On OS X, every time voc produced new macos binary, and every time md5sum of produced binary changed. Then I have checked sums of generated .o object files. They were the same. That means, sums are changing during linking. Indeed, macosx doesn’t use ELF files, but special MACH executables. Linker adds some information which changes each time, like time of the linking.