[concepts.object] Change "built-in" to "fundamental" types (#6012)

Author: ranaanoop

source/concepts.tex

@@ -1205,14 +1205,14 @@
 \pnum
 \begin{note}
 The \libconcept{semiregular} concept is modeled by types that behave similarly
-to built-in types like \tcode{int}, except that they need not
+to fundamental types like \tcode{int}, except that they need not
 be comparable with \tcode{==}.
 \end{note}
 
 \pnum
 \begin{note}
 The \libconcept{regular} concept is modeled by types that behave similarly to
-built-in types like \tcode{int} and that are comparable with
+fundamental types like \tcode{int} and that are comparable with
 \tcode{==}.
 \end{note}
 \end{itemdescr}