[8u] RFR 8226288 - Upgrade to XCode 10+ for building JDK 8u and 11u

[Simon Tooke]

Hello all,

This is a request for review of my patch to enable building 8u with
modern (9,10,11) Xcode versions on macOS.  I've received a few recent
enquiries so I thought I'd submit this.

When I first created this patch is was more for convenience, but soon
macOS will require applications to be "notarized", which cannot be done
with the old version of Xcode.  This will become mandatory long before
8u is due to retire [1].

This patch is not intended to remove the current ability to build 8u on
the current supported build platform.

I have used the patch with Xcode 9,10 and a beta of 11, and used the
resultant JDK to build Graal. 

I have not build a JDK using the old Xcode and this patch; my intent was
to ensure this was still possible.

There is some information available on my GitHub page:
https://github.com/stooke/jdk8u-xcode10

Issue: https://bugs.openjdk.java.net/browse/JDK-8226288

Webrev: http://cr.openjdk.java.net/~stooke/webrevs/jdk-8226288-jdk8u/00/

Previous discussion: 
https://mail.openjdk.java.net/pipermail/jdk8u-dev/2019-June/009733.html 
https://mail.openjdk.java.net/pipermail/jdk8u-dev/2019-July/009760.html

Thank you for your time,

-Simon


[1]
https://developer.apple.com/documentation/security/notarizing_your_app_before_distribution