Fixed valgrind issues with libjpeg-turbo

The fixes are in the updated libjpeg-turbo repository
pulled in by DEPS.  The fixes are detailed in the linked
skia bug.  To summarize briefly, we now use calloc()
instead of malloc().

BUG=skia:4030

Review URL: https://codereview.chromium.org/1237213004
2 files changed