Update PIEX version and adjust the RAW codec accordingly

DEPS

Index: DEPS
diff --git a/DEPS b/DEPS
index 9fe4f6d57d0c1df7b1c7f107d915754ba2dcdea9..667128768be1a6ef2b0762b407b55df8f7dce109 100644
--- a/DEPS
+++ b/DEPS
@@ -22,7 +22,7 @@ deps = {
   "third_party/externals/giflib"  : "https://android.googlesource.com/platform/external/giflib.git@ab10e256df4f684260ca239905b1cec727181f6c",
 
   "third_party/externals/dng_sdk" : "https://android.googlesource.com/platform/external/dng_sdk.git@e95f96bb9d29978211250ee764ba78731ad316df",
-  "third_party/externals/piex"    : "https://android.googlesource.com/platform/external/piex.git@883a1e5419990f51b8e928969e9c5a09869bce0e",
+  "third_party/externals/piex"    : "https://android.googlesource.com/platform/external/piex.git@2f5d8eafb5648056703d6b3dec237d293f75f99e",

[scroggo, 2016/04/13 15:54:31]

In the future, it might be a good idea to update here before updating nyc-dev so
you can get some feedback. It would at least be good to keep them in sync as
much as you can. We've missed bugs in libpng because our tests weren't testing
the latest version shipping in Android :(

[yujieqin, 2016/04/14 07:54:58]

Totally agree!!! It was my fault this time to rush into nyc-dev before doing
here.

 
   "third_party/externals/libjpeg-turbo"             : "https://skia.googlesource.com/third_party/libjpeg-turbo.git@b38b934d246fca482eb6801f4ce79422954a635e",
   # libjpeg-turbo depends on yasm to compile .asm files