[template.valarray.overview] Remove superfluous whitespaces and blank extra line

Author: Andreas-Krug

source/numerics.tex

@@ -7209,10 +7209,9 @@
 namespace std {
   template<class T> class valarray {
   public:
-    using value_type        = T;
-    using iterator          = @\unspec@;
-    using const_iterator    = @\unspec@;
-
+    using value_type     = T;
+    using iterator       = @\unspec@;
+    using const_iterator = @\unspec@;
 
     // \ref{valarray.cons}, construct/destroy
     valarray();