dfa: Remove a redundant forward declaration

[Bruno Haible via Gnulib discussion list]

'struct dfamust' is already defined above.


2026-05-03  Bruno Haible  <br...@clisp.org>

        dfa: Remove a redundant forward declaration.
        * lib/dfa.h: Remove redundant 'struct dfamust' forward declaration.

diff --git a/lib/dfa.h b/lib/dfa.h
index 71a944176e..61e0faf602 100644
--- a/lib/dfa.h
+++ b/lib/dfa.h
@@ -105,8 +105,6 @@ extern void dfacopysyntax (struct dfa *, struct dfa const 
*);
 /* Parse the given string of given length into the given struct dfa.  */
 extern void dfaparse (char const *, idx_t, struct dfa *);
 
-struct dfamust;
-
 /* Free the storage held by the components of a struct dfamust. */
 extern void dfamustfree (struct dfamust *);