RFR: 8215159: Improve initial setup of system Properties

[Mandy Chung]

On 12/10/18 1:17 PM, Claes Redestad wrote:
> Hi,
>
> by inverting the order in which the internal property maps are created,
> we avoid some classloading and get a slightly more efficient code
> execution profile in System.initPhase1.
>
> Webrev: http://cr.openjdk.java.net/~redestad/8215159/jdk.00/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8215159
>

This change looks okay to me.

ModuleBootstrap also removes some `jdk.module.*` private system 
properties during
module system initialization but they are only set if module-related 
command-line
options are set.   These properties are not present in the common 
cases.   These
private system properties are the interface between VM and libraries.   
There is
other mechanism that we can look into to replace using system properties 
in the
future.

Mandy