RFR: 6545422 NativeErrors.java uses wrong path name in exec

[Mattias Tobiasson]

Hi,
Could someone please review this patch?

webrev: http://cr.openjdk.java.net/~ykantser/6545422/webrev.00
bug: https://bugs.openjdk.java.net/browse/JDK-6545422

Changes:
Uses common testlibrary function to find native2ascii binary.
Check null values instead of throwing NullPointerException at different locations. The old version checked null with "assert", which is not always enabled.


Mattias