[ASTImporter] Add test for CXXForRangeStmt

[martong]

LGTM.

test/Import/cxx-for-range/Inputs/F.cpp

+struct Container {
+  int *begin();
+  int *end();
+};
+
+void f() {
+  Container c;
+  for (int varname : c) {
+    return;
+  }
+}

test/Import/cxx-for-range/test.cpp

+// RUN: clang-import-test -dump-ast -import %S/Inputs/F.cpp -expression %s | FileCheck %s
+
+// CHECK: CXXForRangeStmt
+
+// CHECK-NEXT: DeclStmt
+// CHECK-NEXT: VarDecl
+// CHECK-NEXT: DeclRefExpr
+// CHECK-SAME: 'c'
+// CHECK-SAME: Container
+
+// CHECK-NEXT: DeclStmt
+// CHECK-NEXT: VarDecl
+// CHECK-NEXT: CXXMemberCallExpr
+// CHECK-SAME: 'int *'
+// CHECK-NEXT: MemberExpr
+// CHECK-SAME: .begin
+// CHECK-NEXT: DeclRefExpr
+// CHECK-SAME: '__range1'
+// CHECK-SAME: Container
+
+// CHECK-NEXT: DeclStmt
+// CHECK-NEXT: VarDecl
+// CHECK-NEXT: CXXMemberCallExpr
+// CHECK-SAME: 'int *'
+// CHECK-NEXT: MemberExpr
+// CHECK-SAME: .end
+// CHECK-NEXT: DeclRefExpr
+// CHECK-SAME: '__range1'
+// CHECK-SAME: Container
+
+// CHECK-NEXT: BinaryOperator
+// CHECK-SAME: '!='
+// CHECK-NEXT: ImplicitCastExpr
+// CHECK-NEXT: DeclRefExpr
+// CHECK-SAME: '__begin1'
+// CHECK-NEXT: ImplicitCastExpr
+// CHECK-NEXT: DeclRefExpr
+// CHECK-SAME: '__end1'
+
+// CHECK-NEXT: UnaryOperator
+// CHECK-SAME: '++'
+// CHECK-NEXT: DeclRefExpr
+// CHECK-SAME: '__begin1'
+
+// CHECK-NEXT: DeclStmt
+// CHECK-NEXT: VarDecl
+// CHECK-SAME: varname
+
+// CHECK: ReturnStmt
+
+void expr() {
+  f();
+}