Packaging etc.
* Honour XCFLAGS.
* Use `%option nounput' rather than #define YY_NO_UNPUT.
- Patch from Peter Benie, but modified.
+ Patch from Peter Benie.
+ * Specify #define YY_NO_INPUT, which avoids an unused function warning.
+ Patch from Peter Benie.
* Update some copyright notices.
Debian packaging: