[diff.mods.to.definitions] Add entry for 'nullptr_t in stddef.h'

Author: tkoeppe

source/compatibility.tex

@@ -2295,6 +2295,11 @@
 
 Subclause \ref{cwchar.syn} describes the changes.
 
+\pnum
+Header \tcode{<cstddef>}~(\ref{cstddef.syn})\indexlibrary{\idxhdr{cstddef}}
+declares the name \tcode{nullptr_t} in addition to the names declared in
+\tcode{<stddef.h>} in the C standard library.
+
 \rSec2[diff.mods.to.behavior]{Modifications to behavior}
 
 \pnum