Switch to the OpenBSD implementations of the wide scanf functions.

This also gets us the C99 wcstoimax and wcstoumax, and a working fgetwc and
ungetwc, all of which are needed in the implementation.

This also brings several other files closer to upstream.

Change-Id: I23b025a8237a6dbb9aa50d2a96765ea729a85579
diff --git a/libc/bionic/flockfile.cpp b/libc/bionic/flockfile.cpp
index c60497d..3381e8e 100644
--- a/libc/bionic/flockfile.cpp
+++ b/libc/bionic/flockfile.cpp
@@ -29,7 +29,7 @@
 #include <errno.h>
 #include <stdio.h>
 
-#include "fileext.h"
+#include "local.h"
 
 // We can't use the OpenBSD implementation which uses kernel-specific
 // APIs not available on Linux. Instead we use a pthread_mutex_t within