Roll libjpeg_turbo DEPS to r238478

Update libjpeg_turbo to get this CL:
https://codereview.chromium.org/95883002/

BUG=234135

Review URL: https://codereview.chromium.org/99073007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238662 0039d316-1c4b-4281-b951-d872f2087c98
Update .DEPS.git

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238663 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238663