Remove more ODR violations from test code.

PrintAST now works on `library-tests/dataflow/taint-tests`.

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

@@ -2,9 +2,9 @@
 #include "stl.h"
 
 using namespace std;
-
+namespace {
 char *source();
-
+}
 void sink(char *);
 void sink(const char *);
 void sink(bool);

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

@@ -2,9 +2,9 @@
 #include "stl.h"
 
 using namespace std;
-
+namespace {
 char *source();
-
+}
 void sink(char *);
 void sink(std::set<char *>);
 void sink(std::set<char *>::iterator);

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

@@ -2,9 +2,9 @@
 #include "stl.h"
 
 using namespace std;
-
+namespace {
 char *source();
-
+}
 namespace ns_char
 {
 	char source();

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

@@ -2,9 +2,9 @@
 #include "stl.h"
 
 using namespace std;
-
+namespace {
 char *source();
-
+}
 namespace ns_char
 {
 	char source();