SkPDF: allow PDF module to be disabled in DM and SampleApp

tests/DeflateWStream.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 "SkFlate.h"
 #include "SkRandom.h"
 #include "Test.h"
 
+#if SK_SUPPORT_PDF
+
 DEF_TEST(SkDeflateWStream, r) {
     SkRandom random(123456);
     for (int i = 0; i < 50; ++i) {
         uint32_t size = random.nextULessThan(10000);
         SkAutoTMalloc<uint8_t> buffer(size);
         for (uint32_t j = 0; j < size; ++j) {
             buffer[j] = random.nextU() & 0xff;
         }
 
         SkDynamicMemoryWStream dynamicMemoryWStream;
@@ skipping 41 matching lines @@
             uint8_t c;
             SkDEBUGCODE(size_t rb =)decompressed->read(&c, sizeof(uint8_t));
             SkASSERT(sizeof(uint8_t) == rb);
             if (buffer[i] != c) {
                 ERRORF(r, "Decompression failed at byte %u.", (unsigned)i);
                 break;
             }
         }
     }
 }
+#endif  // SK_SUPPORT_PDF