RFR: 8199138: Add RISC-V support to Zero

[John Paul Adrian Glaubitz]

Hi!

This is an updated RFR to add basic RISC-V support to Zero.

This patch is being used for the riscv64 port in Debian.

Please review the changes in [1].

Thanks,
Adrian

> [1] http://cr.openjdk.java.net/~glaubitz/8199138/webrev.00/

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 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz at debian.org
`. `'   Freie Universitaet Berlin - glaubitz at physik.fu-berlin.de
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