Null-terminate the result of a %[..] format

diff --git a/klibc/vsscanf.c b/klibc/vsscanf.c
index 1711438..12a82b2 100644
--- a/klibc/vsscanf.c
+++ b/klibc/vsscanf.c
@@ -349,6 +349,7 @@
 	*sarg++ = *q++;
       }
       if ( q != qq ) {
+	*sarg = '\0';
 	converted++;
       } else {
 	bail = *q ? bail_err : bail_eof;