Dropped use of autoheader in stratego-libraries.

stratego-config.h is no longer installed in the includedir of
strategoxt. There is no configuration option in this file that is
still necessary as part of the strategoxt installation. The mechanism
of config.h installation is rather fragile (some defines have to be
removed), so if it's not necessary anymore, then why not drop it ...

Another reason for this change is that several C files did not
correctly include the generated config.h before aterm2.h. This breaks
on x86-64 systems (STR-698) because aterm2.h requires defines of
various SIZEOF_ variables that now got defined only after the
inclusion of aterm2.h.