Fix the printf family for non-ASCII.

The bug here turned out to be that we hadn't increased the constant
corresponding to the maximum number of bytes in a character to match
our new implementation, so any character requiring more than a byte
in UTF-8 would break our printf family.

Bug: 15439554
Change-Id: I693e5e6eb11c640b5886e848502908ec5fff53b1
diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index 834dcda..483aaf0 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -167,7 +167,7 @@
 extern int	wctomb(char *, wchar_t);
 extern size_t	wcstombs(char *, const wchar_t *, size_t);
 
-#define MB_CUR_MAX 1
+#define MB_CUR_MAX 4U
 
 #if 0 /* MISSING FROM BIONIC */
 extern int on_exit(void (*)(int, void *), void *);