CWG2747 Cannot depend on an already-deleted splice

Also fixes CWG1698.

Author: burblebee

source/lex.tex

@@ -112,8 +112,8 @@
 Line splicing can form
 a \grammarterm{universal-character-name}\iref{lex.charset}.
 \end{note}
-A source file that is not empty and that does not end in a new-line
-character, or that ends in a splice,
+A source file that is not empty and that (after splicing)
+does not end in a new-line character
 shall be processed as if an additional new-line character were appended
 to the file.