RFR(xs): 8220786: Create new switch to redirect error reporting output to stdout or stderr

[Thomas Stüfe]

May I please have reviews for this addition:

cr:
http://cr.openjdk.java.net/~stuefe/webrevs/8220786--create-new-switch-to-redirect-error-reporting-output-to-stdout-or-stderr/webrev.00/webrev/
issue: https://bugs.openjdk.java.net/browse/JDK-8220786
csr: https://bugs.openjdk.java.net/browse/JDK-8220787

This implements the new switches -XX:ErrorFileToStdout/ToStderr. For
details please see the associated CSR and this mailthread:

https://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2019-March/033160.html

Note that I am not sure yet about the CSR state. It has two reviewers, one
of them part of the CSR group. But it is still in proposed state.

Cheers, Thomas