ARM port consolidation

[Bob Vandette]

During the JDK 9 time frame, Oracle open sourced its 32-bit and 64-bit
ARM ports and contributed them to OpenJDK.  These ports have been used for
years in the embedded and mobile market, making them very stable and 
having the benefit of a single source base which can produce both 32 and
64-bit binaries.  The downside of this contribution is that it resulted
in two 64-bit ARM implementations being available in OpenJDK.  

I'd like to propose that we eliminate one of the 64-bit ARM ports and
encourage everyone to enhance and support the remaining 32 and 64 bit
ARM ports. This would avoid the creation of yet another port for these chip
architectures.  The reduction of competing ports will allow everyone
to focus their attention on a single 64-bit port rather than diluting 
our efforts.  This will result in a higher quality and a more performant 
implementation.

The community at large (especially RedHat, BellSoft, Linaro and Cavium)
have done a great job of enhancing and keeping the AArch64 port up to
date with current and new Hotspot features.  As a result, I propose that
we standardize the 64-bit ARM implementation on this port.

If there are no objections, I will file a JEP to remove the 64-bit ARM 
port sources that reside in jdk/open/src/hotspot/src/cpu/arm
along with any build logic.  This will leave the Oracle contributed
32-bit ARM port and the AArch64 64-bit ARM port.

Let me know what you all think,
Bob Vandette