[dcl.init.general] break p7 into two paragraphs (#4912)

Author: jwakely

source/declarations.tex

@@ -4368,6 +4368,7 @@
 no initialization is performed.
 \end{itemize}
 
+\pnum
 A class type \tcode{T} is \defn{const-default-constructible} if
 default-initialization of \tcode{T} would invoke
 a user-provided constructor of \tcode{T} (not inherited from a base class)