Add input JPEG images for djpeg and jpegtran tests

Upstream unit tests use the output of cjpeg tests as input for djpeg
and jpegtran tests. To avoid the coupling of compression and
decompression unit tests, this commit adds the input JPEG images for
the djpeg and jpegtran unit tests to the testimages directory.

These images are generated from the original images in the testimages
directory and are distributed under the same license.

Bug: 993876
Change-Id: I1c08432f8891f71d081df284ff83bbc021d8cb72
diff --git a/README.chromium b/README.chromium
index e281d91..3eff2d7 100644
--- a/README.chromium
+++ b/README.chromium
@@ -83,6 +83,7 @@
   - Refactor cjpeg.c to provide test interface
   - Add gtest wrapper for cjpeg tests
   - Refactor jpegtran.c to provide test interface
+  - Add input JPEG images for djpeg and jpegtran tests
 
 Refer to working-with-nested-repos [1] for details of how to setup your git
 svn client to update the code (for making local changes, cherry picking from