Create nacl_valgrind.h.
Create nacl_valgrind.h.

For untrusted code we have to use a modified variant of valgrind.h,
because we need different assembly sequences there.
More info: http://code.google.com/p/nativeclient/wiki/ValgrindMemcheck

This CL adds file nacl_valgrind.h which has *no* modifications
from the original one. The required modifications will go as separate CLs.

Review URL: http://codereview.chromium.org/1660010

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@2079 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

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