C++: Use unaliased SSA in constant_func.ql test

Author: igfoo

cpp/ql/test/library-tests/ir/constant_func/constant_func.ql

@@ -1,6 +1,6 @@
 import cpp
 import semmle.code.cpp.ir.IR
-import semmle.code.cpp.ir.implementation.aliased_ssa.constant.ConstantAnalysis
+import semmle.code.cpp.ir.implementation.unaliased_ssa.constant.ConstantAnalysis
 import semmle.code.cpp.ir.internal.IntegerConstant
 
 from IRFunction irFunc, int value