Add mode bits to open calls

This was already done internally a while ago, but for us to submit
clang FORTIFY, we need it here, as well.

Bug: 32073964
Test: Clang FORTIFY no longer complains about open calls here.
Change-Id: I72428ac4d3279ffc330ae5aa579960c26703053c
Merged-In: Iaed2538831b19ada26005bbef33cff28209c6512
2 files changed