[vector.bool.pspc] Replace constexpr static with static constexpr

As preferred by our style guide.

Author: CaseyCarter

source/containers.tex

@@ -9238,7 +9238,7 @@
     constexpr iterator erase(const_iterator position);
     constexpr iterator erase(const_iterator first, const_iterator last);
     constexpr void swap(vector&);
-    constexpr static void swap(reference x, reference y) noexcept;
+    static constexpr void swap(reference x, reference y) noexcept;
     constexpr void flip() noexcept;     // flips all bits
     constexpr void clear() noexcept;
   };
@@ -9279,7 +9279,7 @@
 
 \indexlibrarymember{swap}{vector<bool>}%
 \begin{itemdecl}
-constexpr static void swap(reference x, reference y) noexcept;
+static constexpr void swap(reference x, reference y) noexcept;
 \end{itemdecl}
 
 \begin{itemdescr}