[depr.c.macros] Remove superfluous indexing

Author: jensmaurer

source/future.tex

@@ -221,7 +221,6 @@
 
 \pnum
 The header \libheaderref{stdalign.h} has the following macros:
-\indexheader{stdalign.h}%
 \indexlibraryglobal{__alignas_is_defined}%
 \begin{codeblock}
 #define @\xname{alignas_is_defined}@ 1
@@ -230,7 +229,6 @@
 
 \pnum
 The header \libheaderref{stdbool.h} has the following macro:
-\indexheader{stdbool.h}%
 \indexhdr{stdbool.h}%
 \indexlibraryglobal{__bool_true_false_are_defined}%
 \begin{codeblock}