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/pthread_debug.cpp b/libc/bionic/pthread_debug.cpp
index f8f0c59..94c23de 100644
--- a/libc/bionic/pthread_debug.cpp
+++ b/libc/bionic/pthread_debug.cpp
@@ -43,9 +43,7 @@
 #include "bionic_tls.h"
 #include "debug_mapinfo.h"
 #include "debug_stacktrace.h"
-#include "logd.h"
-
-#include <private/debug_format.h>
+#include "libc_logging.h"
 
 /*
  * ===========================================================================