RFR (tedious) 8216022: Use #pragma once

[coleen.phillimore at oracle.com]

Here is the webrev and bug link.

open webrev at http://cr.openjdk.java.net/~coleenp/8216022.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8216022

On 1/2/19 9:16 PM, coleen.phillimore at oracle.com wrote:
> Summary: change include guards to #pragma once, except in generated 
> header files.
>
> Tested with mach5 for linux-x64{-debug}, solaris-sparc, macosx-x64, 
> windows-x64, built aarch64 with cross compiler, and zero.
>
> Ran tier1 and 2 tests.
>
> The webrev is huge but there are only 3 lines changed in each header 
> file.  So click on the patch.
>
> I'll update the copyright headers with a script with the commit. Also, 
> will do this after the shenandoah copyright headers are fixed.
>
> Adrian: I included you to check your platforms.
>
> Happy New Year!
> Coleen