Don't use printf %n.

Index: lib/vasnprintf.c
--- lib/vasnprintf.c.orig
+++ lib/vasnprintf.c
@@ -4871,10 +4871,7 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp,
 #endif
                   *fbp = dp->conversion;
 #if USE_SNPRINTF
-# if ! (((__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 3))        \
-         && !defined __UCLIBC__)                                            \
-        || (defined __APPLE__ && defined __MACH__)                          \
-        || (defined _WIN32 && ! defined __CYGWIN__))
+# if 0
                 fbp[1] = '%';
                 fbp[2] = 'n';
                 fbp[3] = '\0';