slang: Don't build as Universal Binary (see issue #23).

Don't build S-lang as Universal Binary on Snow Leopard, due:
S-Lang Library not built properly.  Fix SIZEOF_* in config.h and recompile

Signed-off-by: Rudá Moura <ruda.moura@gmail.com>
Merge pull request #34 from ruda/slang-issue-23

slang: Don't build as Universal Binary (see issue #23).