RFR: 8222819: Remove setting of headless property on MacOS from launcher code.

[Phil Race]

Bug: https://bugs.openjdk.java.net/browse/JDK-8222819
Webrev: http://cr.openjdk.java.net/~prr/8222819/

After fixing https://bugs.openjdk.java.net/browse/JDK-8130266 the code
in the launcher which sets the java.awt.headless property on MacOS is 
defunct
since the java.desktop module figures it out for itself.
I did manual verification that this is still true by ssh'ing into a Mac 
system

So this is a clean up fix to remove the now unnecessary launcher code.

-phil.