Fix return values of updateListBoxHook

Since abff960 (saving results to improve time, 2015-11-18) the function
ceased to return a proper return value. This return value is used by
showCode to determine if a procedure file does not contain any parseable
content and should thus immediately opened when selected.

Author: t-b

procedures/CodeBrowser.ipf

@@ -839,6 +839,8 @@ Function updateListBoxHook()
 	else
 		sortListByLineNumber(decls, lines)
 	endif
+
+	return DimSize(decls, 0)
 End
 
 // Shows the line/function for the function/macro with the given index into decl