RFR [XS] : 8230856: Java_java_net_NetworkInterface_getByName0 on unix misses ReleaseStringUTFChars in early return

[Baesken, Matthias]

Hello,  please review this small fix .
It  adds a missing   ReleaseStringUTFChars in  an early return   case  in 
function  Java_java_net_NetworkInterface_getByName0
(unix only) .

Bug/webrev :

https://bugs.openjdk.java.net/browse/JDK-8230856

http://cr.openjdk.java.net/~mbaesken/webrevs/8230856.0/


Thanks, Matthias