[stdckdint.h.syn,stdbit.h.syn] Add proper indexing for header definition

Also add a check to prevent future oversights.

Author: jensmaurer

source/numerics.tex

@@ -18952,6 +18952,7 @@
 
 \rSec2[stdckdint.h.syn]{Header \tcode{<stdckdint.h>} synopsis}
 
+\indexheader{stdckdint.h}%
 \begin{codeblock}
 #define @\libglobal{__STDC_VERSION_STDCKDINT_H__}@ 202311L
 

source/utilities.tex

@@ -15483,6 +15483,7 @@
 
 \rSec1[stdbit.h.syn]{Header \tcode{<stdbit.h>} synopsis}
 
+\indexheader{stdbit.h}%
 \begin{codeblock}
 #define @\libglobal{__STDC_VERSION_STDBIT_H__}@ 202311L
 

tools/check-output.sh

@@ -48,6 +48,12 @@ cat std-grammarindex.ind |
     sed 's/^\(.*\)$/grammar non-terminal \1 has no definition/' |
     fail || failed=1
 
+# Find header index entries missing a definition
+cat std-headerindex.ind |
+    awk 'BEGIN { def=1 } /^  .item/ { if (def==0) { gsub("[{},]", "", item); print item } i=NF; while (i > 0 && $i !~ "<[a-z_.]*>") { --i; } item=$i; def=0; next } /hyperindexformat/ { def=1 }' |
+    sed 's/^\(.*\)$/header \1 has no definition/' |
+    fail || failed=1
+
 # Find concept index entries missing a definition
 cat std-conceptindex.ind |
     sed 's/.hyperindexformat/\nhyperindexformat/;s/.hyperpage/hyperpage/' |