Duplicate label fix.

Doc/lib/libctypes.tex

@@ -2113,7 +2113,7 @@ debugging; never modify the contents of this dictionary.
 \end{memberdesc}
 
 
-\subsubsection{Fundamental data types\label{ctypes-fundamental-data-types}}
+\subsubsection{Fundamental data types\label{ctypes-fundamental-data-types-2}}
 
 \begin{classdesc*}{_SimpleCData}
 This non-public class is the base class of all fundamental ctypes