RFR(S): 7200277 [parfait] potential buffer overflow in npt/utf.c

[Staffan Larsen]

Please review this change to avoid a buffer overflow in npt/utf.c.

webrev: http://cr.openjdk.java.net/~sla/7200277/webrev.00/
bug: https://bugs.openjdk.java.net/browse/JDK-7200277

Thanks,
/Staffan