stdin/stdout/stderr are special; their mutexes are initialized by
__sinit. There's no unit test for this, because __sinit has already
been called by the time the first unit test runs, but you could
reproduce this failure with a trivial main() that calls flockfile
or ftrylockfile on one of the standard streams before otherwise
using stdio.
Bug: 18208568
(cherry picked from commit c48c3e4bb3d1665f3e9fa2785daafa72dfe59399)
Change-Id: Ia0c43ed4ac69daea8152aee9516415a6e3f8a042
432f645887