Report mutation for a static var mutated indirectly via a reference field in a class.

TEST(PotentialFavorMutationTest, NestedStructInFunctionPtrMutation) {
  const auto ast = buildASTFromCode("void f() {"
                                    "  static int x{0};"
                                    "  struct S { int* ptr = &x; void m() {*ptr=1;} } s;"
                                    "  s.m();"
                                    "}");
  const auto ResultDecl = match(withEnclosingCompound(declName("x")), ast->getASTContext());
  EXPECT_TRUE(isDeclMutated(ResultDecl, ast.get()));
}

TEST(PotentialFavorMutationTest, NestedStructInFunctionRefMutation) {
  const auto ast = buildASTFromCode("void f() {"
                                    "  static int x{0};"
                                    "  struct S { int& ref = x; void m() {ref=1;} } s;"
                                    "  s.m();"
                                    "}");
  const auto ResultDecl = match(withEnclosingCompound(declName("x")), ast->getASTContext());
  EXPECT_TRUE(isDeclMutated(ResultDecl, ast.get()));
}