We only need one logging API, and I prefer the one that does no
allocation and is thus safe to use in any context.
Also use O_CLOEXEC when opening the /dev/log files.
Move everything logging-related into one header file.
Change-Id: Ic1e3ea8e9b910dc29df351bff6c0aa4db26fbb58
In particular this affects assert(3) and __cxa_pure_virtual, both of
which have managed to confuse people this week by apparently aborting
without reason. (Because stderr goes nowhere, normally.)
Bug: 6852995
Bug: 6840813
Change-Id: I7f5d17d5ddda439e217b7932096702dc013b9142
