NaCl: Re-enable ASLR for nacl-loader processes on Mac OS X

When Mac Chrome was 32-bit, we needed to disable ASLR for NaCl because
otherwise address space would get fragmented and we wouldn't be able
to allocate enough contiguous address space (issue 90221).

This is no longer necessary now that Mac Chrome is 64-bit (issue
18323).

BUG=90221
BUG=18323
TEST=browser_tests

Review URL: https://codereview.chromium.org/1312273002

Cr-Commit-Position: refs/heads/master@{#345704}
2 files changed