Fix possible crash in AllocArgs.
Fix possible crash in AllocArgs.

memset will crash on NULL pointer. Use calloc instead.

BUG=none
TEST=bots

Review URL: https://chromiumcodereview.appspot.com/18344003

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@11654 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client