[common.iter.types] Avoid "defining" typedef-names

Use "determine" instead.

Author: frederick-vs-ja

source/iterators.tex

@@ -5527,7 +5527,7 @@
 \pnum
 The nested \grammarterm{typedef-name} \tcode{iterator_category} of
 the specialization of \tcode{iterator_traits} for \tcode{common_iterator<I, S>}
-is defined if and only if \tcode{iter_difference_t<I>} is an integral type.
+is declared if and only if \tcode{iter_difference_t<I>} is an integral type.
 In that case,
 \tcode{iterator_category} denotes \tcode{forward_iterator_tag} if
 the \grammarterm{qualified-id} \tcode{iterator_traits<I>::iterator_category}
@@ -5537,7 +5537,7 @@
 
 \pnum
 The remaining nested \grammarterm{typedef-name}s of the specialization of
-\tcode{iterator_traits} for \tcode{common_iterator<I, S>} are defined as follows:
+\tcode{iterator_traits} for \tcode{common_iterator<I, S>} are determined as follows:
 \begin{itemize}
 \item
 \tcode{iterator_concept} denotes \tcode{forward_iterator_tag}