separate DDict logic into its own module

created zstd_ddict.c within lib/decompress

build/VS2010/fullbench/fullbench.vcxproj

@@ -176,6 +176,7 @@
     <ClCompile Include="..\..\..\lib\compress\zstd_ldm.c" />
     <ClCompile Include="..\..\..\lib\decompress\huf_decompress.c" />
     <ClCompile Include="..\..\..\lib\decompress\zstd_decompress.c" />
+    <ClCompile Include="..\..\..\lib\decompress\zstd_ddict.c" />
     <ClCompile Include="..\..\..\programs\datagen.c" />
     <ClCompile Include="..\..\..\programs\bench.c" />
     <ClCompile Include="..\..\..\tests\fullbench.c" />
@@ -196,6 +197,7 @@
     <ClInclude Include="..\..\..\lib\compress\zstd_opt.h" />
     <ClInclude Include="..\..\..\lib\compress\zstd_ldm.h" />
     <ClInclude Include="..\..\..\lib\compress\zstdmt_compress.h" />
+    <ClCompile Include="..\..\..\lib\decompress\zstd_ddict.h" />
     <ClInclude Include="..\..\..\lib\legacy\zstd_legacy.h" />
     <ClInclude Include="..\..\..\programs\datagen.h" />
     <ClInclude Include="..\..\..\programs\util.h" />