[xrefdelta] Fix unresolved reference.

Author: zygoloid

source/xrefdelta.tex

@@ -157,7 +157,7 @@
 \movedxref{class.copy}{class.mem}
 
 % Top-level clause merging caused some Annex A subclauses to vanish.
-\movedxref{gram.decl}{gram.dcl.decl}
+\movedxref{gram.decl}{gram.dcl}
 \movedxref{gram.derived}{gram.class}
 \movedxref{gram.special}{gram.class}