Add SK_SUPPORT_LEGACY_DRAWFILTER guard around calls to SkCanvas::(get|set)DrawFilter.

tests/DrawFilterTest.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCanvas.h"
 #include "SkDrawFilter.h"
 #include "SkSurface.h"
 #include "Test.h"
 
+#ifdef SK_SUPPORT_LEGACY_DRAWFILTER
+
 namespace {
 class TestFilter : public SkDrawFilter {
 public:
     bool filter(SkPaint* p, Type) override {
         return true;
     }
 };
 }
 
 /**
@@ skipping 13 matching lines @@
     canvas->setDrawFilter(df);
     REPORTER_ASSERT(reporter, nullptr != canvas->getDrawFilter());
     canvas->restore();
 
     REPORTER_ASSERT(reporter, nullptr == canvas->getDrawFilter());
 }
 
 DEF_TEST(DrawFilter, reporter) {
     test_saverestore(reporter);
 }
+
+#endif