Only use JDCT_FAST if it is supported in jpeg.

src/images/SkImageDecoder_libjpeg.cpp

Index: src/images/SkImageDecoder_libjpeg.cpp
diff --git a/src/images/SkImageDecoder_libjpeg.cpp b/src/images/SkImageDecoder_libjpeg.cpp
index 4f32aa918614c8e72afd9cd4a7f59e5335ac3f62..b3dde476c8d3ca9cec8797724663e135f80b43a0 100644
--- a/src/images/SkImageDecoder_libjpeg.cpp
+++ b/src/images/SkImageDecoder_libjpeg.cpp
@@ -268,11 +268,15 @@ bool SkJPEGImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
     */
     int sampleSize = this->getSampleSize();
 
+#ifdef DCT_IFAST_SUPPORTED
     if (this->getPreferQualityOverSpeed()) {
         cinfo.dct_method = JDCT_ISLOW;
     } else {
         cinfo.dct_method = JDCT_IFAST;
     }
+#else
+    cinfo.dct_method = JDCT_ISLOW;
+#endif
 
     cinfo.scale_num = 1;
     cinfo.scale_denom = sampleSize;