GitLab

The definition of nacl_irt_icache was moved to irt.h in the NaCl repository,
so irt_nonsfi.h is no longer necessary.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4033

Review URL: https://codereview.chromium.org/935743004

Cr-Commit-Position: refs/heads/master@{#317728}