[over.match.oper] Replace "member, non-member, and built-in candidates"

with "non-rewritten candidates"

This simplifies the wording, implicitly explains why we're considering
only some candidates, and avoids overtly suggesting that we could ever
pick a reversed-parameter-order built-in candidate.

source/overloading.tex

@@ -1083,7 +1083,7 @@
 \item
 For the relational\iref{expr.rel} operators,
 the rewritten candidates include
-all member, non-member, and built-in candidates
+all non-rewritten candidates
 for the expression \tcode{x <=> y}.
 \item
 For the
@@ -1093,19 +1093,19 @@
 the rewritten candidates also include
 a synthesized candidate,
 with the order of the two parameters reversed,
-for each member, non-member, and built-in candidate
+for each non-rewritten candidate
 for the expression
 \tcode{y <=> x}.
 \item
 For the \tcode{!=} operator\iref{expr.eq},
 the rewritten candidates
-include all member, non-member, and built-in candidates
+include all non-rewritten candidates
 for the expression \tcode{x == y}.
 \item
 For the equality operators,
 the rewritten candidates also include a synthesized candidate,
 with the order of the two parameters reversed,
-for each member, non-member, and built-in candidate
+for each non-rewritten candidate
 for the expression \tcode{y == x}.
 \item
 For all other operators, the rewritten candidate set is empty.