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
diff --git a/libc/bionic/__strlcpy_chk.cpp b/libc/bionic/__strlcpy_chk.cpp
index 62fa14b..636966b 100644
--- a/libc/bionic/__strlcpy_chk.cpp
+++ b/libc/bionic/__strlcpy_chk.cpp
@@ -28,7 +28,7 @@
 
 #include <string.h>
 #include <stdlib.h>
-#include <private/logd.h>
+#include "libc_logging.h"
 
 /*
  * __strlcpy_chk. Called in place of strlcpy() when we know the