[PATCH:libXaw3d] Make laygram.y compatible with bison 2.3 and older

[Rafał Mużyło]

Well, I've put all the LayYY stuff there due to 'nm -C -D' output
- that's the place where you see the difference between setting the
prefix and leaving the default one.
Also, you've probably didn't check the resulting lib with 'ldd -r'
- it would have complained due to Layout.c.

As I already mentioned at some point, I don't think that those symbols
should have been exported in the first place, but both libXaw and
libXaw3d are quite messy in that regard.