In C++ you don't have to say 'struct' or 'class' if the declaration of
the type has been seen. Some compilers will complain if you use
'struct' when 'class' should have been used and vice versa.
Fixes bugzilla #29539.
The mesa build environment does not (currently) accept external
dependencies such as flex and bison. The compromise is to commit the
generated output files, (in spite of the pain that comes from having
generated files under version control).
