Avoid unneeded pampering of generated lex file.

Avoid unneeded pampering of generated lex file.

In order to support slint-checking of lex generated file, that file
(only one) was not automatically handled by automake, but was custom
generated by adding splint specific declarations. Yet it seems checking
of generated files doesn't happen for some time, so this pampering is
superfluous. Removed such pampering and let automake handled it.

Additionally, there is no need to use a trivial yywrapper in the
generated lex code -- added lex option to avoid the need for such a
wrapper, and removed forward declaration (and Win32 implementation) and
also the additional linking requirement.