__open_2() is used by the fortify implementation of open(2) in
fcntl.h, and as such needs an unmangled C name. For some reason
(inlining?), this doesn't cause problems at the default optimization
level, but does for -O0.
The rest of these didn't cause build failures, but they look suspect
and probably will, we just haven't caught them yet.
(cherry-pick of 658727e111ed6dee7be5239494f0764f7b1b02f8 with conflicts
in stdio.h and string.h.)
Bug: 17784968
Change-Id: I7391a7a8999ee204eaf6abd14a3d5373ea419d5b
55ee845b8e