do better wrt coverage bot.
do better wrt coverage bot.

On a coverage bot build, the meaning of NaClAbort is subverted --
instead of invoking abort(), it exit(-SIGABRT).

TBR=ncbray@google.com
BUG= None
TEST= None

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@8910 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client,nacl-webkit/native_client,nacl-webkit/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client