[gslice.cons] Fix indentation in itemdecl for gslice.

Author: Dawn Perchik

source/numerics.tex

@@ -8491,7 +8491,7 @@
 \begin{itemdecl}
 gslice();
 gslice(size_t start, const valarray<size_t>& lengths,
-         const valarray<size_t>& strides);
+       const valarray<size_t>& strides);
 gslice(const gslice&);
 \end{itemdecl}