argv_data would leak if the argv_ allocation failed or the MAX_ARGC cap
was hit
Tested:
for i in `seq 1 171`; do
export MALLOC_FAIL_AT=$i
./examples/img2webp jpeg_file -o /dev/null
./examples/img2webp -mixed jpeg_file -o /dev/null
done
Change-Id: I39864691e96d5456f324d95a3653bba0f6d6a7be