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

tests/PDFJpegEmbedTest.cpp

Index: tests/PDFJpegEmbedTest.cpp
diff --git a/tests/PDFJpegEmbedTest.cpp b/tests/PDFJpegEmbedTest.cpp
index cfe6776bf5b22f8dedd3cbfd35c66ac7fd79fe56..021161bf9f09b16017f0048aee7e6b55ed45568a 100644
--- a/tests/PDFJpegEmbedTest.cpp
+++ b/tests/PDFJpegEmbedTest.cpp
@@ -14,6 +14,8 @@
 #include "Resources.h"
 #include "Test.h"
 
+#if SK_SUPPORT_PDF
+
 // Returned bitmap is lazy.  Only lazy bitmaps hold onto the original data.
 static SkBitmap bitmap_from_data(SkData* data) {
     SkASSERT(data);
@@ -125,3 +127,4 @@ DEF_TEST(JpegIdentification, r) {
         }
     }
 }
+#endif  // SK_SUPPORT_PDF