RFR 8158023: SocketExceptions contain too little information sometimes

[Langer, Christoph]

Hi all,

please review the following change:
Webrev: http://cr.openjdk.java.net/~clanger/webrevs/8158023.1/
Bug: https://bugs.openjdk.java.net/browse/JDK-8158023

During error analysis I stumbled over a place where I encountered a SocketException which was thrown along with some strerror information as message. I found it hard to find the originating code spot with that information.

So I looked at the places where we throw exceptions, namely JNU_Throw... and NET_Throw... functions and came up with the following enhancement:
- NET_ThrowByNameWithLastError can go completely as it does not provide any benefit over JNU_ThrowByNameWithLastError.
- JNU_ThrowByNameWithLastError can be cleaned up.

- I added JNU_ThrowByNameWithMessageAndLastError to print out a string like message + ": " + last error.

- I went over all places where NET_ThrowByNameWithLastError is used and replaced it appropriately.

Do you think this change is desirable/possible?

Though it's mainly a net topic, I'm posting it to nio-dev and core-libs-dev as well as JNU_Throw... code affects all.

Best regards
Christoph