configure_linux_arm.mk should integrate with openJDK configure

[JamesKingdon]

The settings for the cross compiler tool chain and global includes in configure_linux_arm.mk (and compiler flags in rules.linux.mk) need to be settable from the openJDK configure settings as we currently have the same information redundantly scattered across four or five files.

[mgaudet]

I suspect this issue would be better served at https://github.com/eclipse/openj9, even if the ultimate code change happens in OMR...

[JamesKingdon]

@mgaudet I also opened eclipse-openj9/openj9#518 to cover openj9 specifics.

[JamesKingdon]

I've addressed this issue via #2057

That fix might be considered a temporary step as instead of integrating with the openJDK configure it gets the necessary information from environment variables provided by the Docker image.