C++: Directly import AST GVN module in tests

Author: MathiasVP

cpp/ql/test/library-tests/valuenumbering/GlobalValueNumbering/Uniqueness.ql

@@ -1,5 +1,5 @@
 import cpp
-import semmle.code.cpp.valuenumbering.GlobalValueNumbering
+import semmle.code.cpp.valuenumbering.GlobalValueNumberingImpl
 
 // Every expression should have exactly one GVN.
 // So this query should have zero results.

cpp/ql/test/library-tests/valuenumbering/GlobalValueNumbering/diff_ir_expr.ql

@@ -1,5 +1,5 @@
 import cpp
-import semmle.code.cpp.valuenumbering.GlobalValueNumbering as AST
+import semmle.code.cpp.valuenumbering.GlobalValueNumberingImpl as AST
 import semmle.code.cpp.ir.internal.ASTValueNumbering as IR
 import semmle.code.cpp.ir.IR