C++: Fix 'strtok' model.

cpp/ql/lib/semmle/code/cpp/models/implementations/Strtok.qll

@@ -32,6 +32,8 @@ private class Strtok extends ArrayFunction, AliasFunction, TaintFunction, SideEf
 
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     input.isParameter(0) and output.isReturnValue()
+    or
+    input.isParameterDeref(0) and output.isReturnValueDeref()
   }
 
   override predicate hasOnlySpecificReadSideEffects() { none() }

cpp/ql/test/library-tests/dataflow/taint-tests/taint.cpp

@@ -718,6 +718,6 @@ void test_strtok_indirect() {
 	char *source = indirect_source();
 	const char* delim = ",.-;:_";
 	char* tokenized = strtok(source, delim);
-	sink(*tokenized); // $ MISSING: ast,ir
+	sink(*tokenized); // $ ir MISSING: ast
 	sink(*delim);
 }