Textual change to make the doc reflect reality

Doc/lib/libpdb.tex

@@ -393,7 +393,7 @@ function.
 
 \item[\code{'c_call'}]
 A C function is about to be called.  This may be an extension function
-or a builtin.  \var{arg} is the C function name.
+or a builtin.  \var{arg} is the C function object.
 
 \item[\code{'c_return'}]
 A C function has returned. \var{arg} is \code{None}.