hg: jdk/sandbox: 8221988: add possibility to build with Visual Studio 2019

[chris.hegarty at oracle.com]

Changeset: 14615b8ac24c
Author:    avoitylov
Date:      2019-04-26 18:56 +0300
URL:       http://hg.openjdk.java.net/jdk/sandbox/rev/14615b8ac24c

8221988: add possibility to build with Visual Studio 2019
Reviewed-by: erikj, ysuenaga

! doc/building.html
! doc/building.md
! make/autoconf/toolchain_windows.m4
+ make/devkit/createWindowsDevkit2019.sh