RFR 8251715 : Throw UncheckedIOException in place of InternalError when HttpClient fails due to unavailability of underlying resources required by SSLContext.

[Rahul Yadav]

Hello,

Request to have my fix reviewed for issue:

JDK-8251715:  Throw UncheckedIOException in place of InternalError when 
HttpClient fails due to unavailability of underlying resources required 
by SSLContext.

This fix updates jdk.internal.net.http.HttpClientImpl to throw an 
UncheckedIOException instead of InternalError,
in this case, when `SSLContext.getDefault()` fails due to unavailability 
of underlying resources.

Issue:  https://bugs.openjdk.java.net/browse/JDK-8251715
webrev: http://cr.openjdk.java.net/~ryadav/webrev_8251715/index.html


- rahul