[stmt] Move start of subclause-spanning index entries up to \rSec1

I expect that we forgot to move this when we added the "general"
subclauses to remove hanging paragraphs, and thus accidentally caused
the index entries to be "misnested".

Author: tkoeppe

source/statements.tex

@@ -245,9 +245,9 @@
 \end{note}
 
 \rSec1[stmt.select]{Selection statements}%
+\indextext{statement!selection|(}
 
 \rSec2[stmt.select.general]{General}%
-\indextext{statement!selection|(}
 
 \pnum
 Selection statements choose one of several flows of control.
@@ -500,9 +500,9 @@
 \indextext{statement!selection|)}
 
 \rSec1[stmt.iter]{Iteration statements}%
+\indextext{statement!iteration|(}
 
 \rSec2[stmt.iter.general]{General}%
-\indextext{statement!iteration|(}
 
 \pnum
 Iteration statements specify looping.
@@ -777,6 +777,7 @@
 each \grammarterm{decl-specifier} shall be either a \grammarterm{type-specifier}
 or \keyword{constexpr}. The \grammarterm{decl-specifier-seq} shall not define a
 class or enumeration.%
+
 \indextext{statement!iteration|)}
 
 \rSec1[stmt.jump]{Jump statements}%