untrusted.gypi: Allow translate_flags to be set by other gyp files.
untrusted.gypi: Allow translate_flags to be set by other gyp files.

That way, we can specify 'translate_flags': [ '-O0' ] on a per-target basis.

Used by: https://codereview.chromium.org/12913014/

BUG=none

Review URL: https://codereview.chromium.org/12983008

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@11050 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