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/stdio/findfp.c b/libc/stdio/findfp.c
index 926e5a1..2dd32c9 100644
--- a/libc/stdio/findfp.c
+++ b/libc/stdio/findfp.c
@@ -61,11 +61,7 @@
 static struct glue *lastglue = &uglue;
 _THREAD_PRIVATE_MUTEX(__sfp_mutex);
 
-static struct __sfileext __sFext[3] = {
-	_FILEEXT_INITIALIZER,
-	_FILEEXT_INITIALIZER,
-	_FILEEXT_INITIALIZER,
-};
+static struct __sfileext __sFext[3];
 
 FILE __sF[3] = {
 	std(__SRD, STDIN_FILENO),		/* stdin */