distcheck fails with --disable-css
Because dist ignores ENABLE conditionals, it always lists .y and .l files in DIST_SOURCES
Because of this, it tries to build from the y file but without passing $YACC to ylwrap, only passing AM_YFLAGS options, and fails.
That's total mess due to the fact we're in maintainer mode and bison / lex support is only considered as mandatory tools for the whole source.
Solving this using custom build rules might rise new issues:
- tests for lex/yacc might still trigger build on .y files
- it's unclean if we can still get installs of ylwrap (which is a mandatory for proper wrapping of those unsafe tools)