C++: Fix test breaks due to private imports of cpp

cpp/ql/src/Likely Bugs/RedundantNullCheckSimple.ql

@@ -16,6 +16,7 @@
  * LGTM until its performance is well understood.
  */
 
+import cpp
 import semmle.code.cpp.ir.IR
 import semmle.code.cpp.ir.ValueNumbering
 

cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowDispatch.qll

@@ -1,3 +1,4 @@
+private import cpp
 private import semmle.code.cpp.ir.IR
 
 Function viableImpl(CallInstruction call) { result = viableCallable(call) }