Add dm target to BUILD and refactor BUILD file. Fix blaze compilation errors.

src/codec/SkCodec_libpng.cpp

Index: src/codec/SkCodec_libpng.cpp
diff --git a/src/codec/SkCodec_libpng.cpp b/src/codec/SkCodec_libpng.cpp
index 7d41623a887f2e18a85cd8ff8e962395dced8d57..3b105de427788558993ac86a5a2e824f598943c4 100644
--- a/src/codec/SkCodec_libpng.cpp
+++ b/src/codec/SkCodec_libpng.cpp
@@ -605,8 +605,8 @@ public:
     SkPngScanlineDecoder(const SkImageInfo& srcInfo, SkStream* stream,
             png_structp png_ptr, png_infop info_ptr, int bitDepth)
         : INHERITED(srcInfo, stream, png_ptr, info_ptr, bitDepth, 1)
-        , fSrcRow(nullptr)
         , fAlphaState(kUnknown_AlphaState)
+        , fSrcRow(nullptr)
     {}
 
     Result onStartScanlineDecode(const SkImageInfo& dstInfo, const Options& options,
@@ -843,4 +843,3 @@ SkCodec* SkPngCodec::NewFromStream(SkStream* stream) {
     return new SkPngInterlacedScanlineDecoder(imageInfo, streamDeleter.detach(), png_ptr,
                                               info_ptr, bitDepth, numberPasses);
 }
-