[out.ptr.t] Fix bullet placement for item that starts with codeblock (#7173)

Author: Eelis

source/memory.tex

@@ -5176,6 +5176,8 @@
 Then, equivalent to:
 \begin{itemize}
 \item
+% pretend to \item that there is real text here, but undo the vertical spacing
+\mbox{}\vspace{-\baselineskip}\vspace{-\parskip}
 \begin{codeblock}
 s.reset();
 \end{codeblock}