[ASTImporter] Add test for ForStmt and ContinueStmt

cfe/trunk/test/Import/for-stmt/Inputs/F.cpp

+void f() {
+  for (;;)
+    ;
+  for (int i = 0;;)
+    continue;
+  for (int i = 0; i != 0; ++i) {
+    i++;
+  }
+}

cfe/trunk/test/Import/for-stmt/test.cpp

+// RUN: clang-import-test -dump-ast -import %S/Inputs/F.cpp -expression %s | FileCheck %s
+
+// CHECK: ForStmt
+// CHECK-NEXT: <<NULL>>
+// CHECK-NEXT: <<NULL>>
+// CHECK-NEXT: <<NULL>>
+// CHECK-NEXT: <<NULL>>
+// CHECK-NEXT: NullStmt
+
+// CHECK: ForStmt
+// CHECK-NEXT: DeclStmt
+// CHECK-NEXT: VarDecl
+// CHECK-NEXT: IntegerLiteral
+// CHECK-NEXT: <<NULL>>
+// CHECK-NEXT: <<NULL>>
+// CHECK-NEXT: <<NULL>>
+// CHECK-NEXT: ContinueStmt
+
+// CHECK: ForStmt
+// CHECK-NEXT: DeclStmt
+// CHECK-NEXT: VarDecl
+// CHECK-NEXT: IntegerLiteral
+// CHECK-NEXT: <<NULL>>
+
+// CHECK-NEXT: BinaryOperator
+// CHECK-NEXT: ImplicitCastExpr
+// CHECK-NEXT: DeclRefExpr
+// CHECK-NEXT: IntegerLiteral
+
+// CHECK-NEXT: UnaryOperator
+// CHECK-SAME: '++'
+// CHECK-NEXT: DeclRefExpr
+
+// CHECK-NEXT: CompoundStmt
+
+void expr() {
+  f();
+}