[meta.rel] Add parentheses for consistency

Parentheses are used for is_pointer_interconvertible_base_of.

Author: jensmaurer

source/meta.tex

@@ -1419,7 +1419,7 @@
  without regard to cv-qualifiers            &
  If \tcode{Base} and
  \tcode{Derived} are non-union class types and are
-not possibly cv-qualified versions of the same type,
+not (possibly cv-qualified versions of) the same type,
  \tcode{Derived} shall be a complete
  type.
  \begin{tailnote}