Clean up internal libc logging.

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
48 files changed