[clang][dataflow] Use IntegerValue instead of StructValue in ValueTest.

Soon, it will no longer be possible to default-construct `StructValue`. For details, see https://discourse.llvm.org/t/70086.

For completeness, also add a test that `areEquivalentValues()` on different `IntegerValue`s returns false.

Reviewed By: xazax.hun, gribozavr2

Differential Revision: https://reviews.llvm.org/D154934

Author: martinboehme

clang/unittests/Analysis/FlowSensitive/ValueTest.cpp

@@ -19,10 +19,16 @@ using namespace clang;
 using namespace dataflow;
 
 TEST(ValueTest, EquivalenceReflexive) {
-  StructValue V;
+  IntegerValue V;
   EXPECT_TRUE(areEquivalentValues(V, V));
 }
 
+TEST(ValueTest, DifferentIntegerValuesNotEquivalent) {
+  IntegerValue V1;
+  IntegerValue V2;
+  EXPECT_FALSE(areEquivalentValues(V1, V2));
+}
+
 TEST(ValueTest, AliasedReferencesEquivalent) {
   auto L = ScalarStorageLocation(QualType());
   ReferenceValue V1(L);