RFR 8007606 : Handle realloc() failure in unix/native/libnet/net_util_md.c correctly

[Ivan Gerasimov]

Hello!

This seems to be the last use of realloc() without proper handling of a 
failure.

Would you please help review a trivial fix?

BUGURL: https://bugs.openjdk.java.net/browse/JDK-8007606
WEBREV: http://cr.openjdk.java.net/~igerasim/8007606/00/webrev/

Thanks in advance!

-- 
With kind regards,
Ivan Gerasimov