RFR: 8326306: RISC-V: Re-structure MASM calls and jumps

[Robbin Ehn]

Hi, please consider.

We have code that directly use the asm for call/jumps instead masm.
Our masm have a bit odd naming, and we don't use 'proper' pseudoinstructions/mnemonics.
Suggested by [riscv-asm-manual](https://github.com/riscv-non-isa/riscv-asm-manual/tree/master)

j offset	jal x0, offset	Jump
jal offset	jal x1, offset	Jump and link
jr rs	        jalr x0, rs, 0	Jump register
jalr rs	        jalr x1, rs, 0	Jump and link register
ret	        jalr x0, x1, 0	Return from subroutine
call offset	auipc x1, offset[31:12]; jalr x1, x1, offset[11:0]	Call far-away subroutine	
tail offset	auipc x6, offset[31:12]; jalr x0, x6, offset[11:0]	Tail call far-away subroutine

But these can only be implemented like this if you have small enough application.
The fallback of these is to use GOT (your C compiler should place a copy of GOT every 2G so it's always reachable).
We don't have GOT, instead we materialize, so there is still differences between these and ours.

This patch:
- Tries to follow these suggested mappings as good we can.
- Make sure all jumps/calls go through MASM. (so we get control and can easily change for sites using a certain calling convention)
- To avoid confusion between MASM public/private methods and ASM methods and the mnemonics there are some renaming.
  E.g. the mnemonics jal means call offset, as we can't use that so there is no 'jal'.
- I enabled c.j, but right now we never generate it.
- As always the macro does no good and are legacy from when code base did not use templates. (also the x-macros screws up my IDE (vim+rtags))

I started down this path due to I have followup patch on top of this which removes trampoline in favor for load-n-jump.
(WIP: https://github.com/robehn/jdk/compare/jal-fixes...robehn:jdk:load-n-link?expand=1)
While looking into our calls it was a bit confusing, this helps. 

Done a couple of t1-3 slightly different version of this patch, and as part of the followup, no issues found. (VF2, qemu, LP4)
Re-running tests, had some last minute changes.

Thanks, Robbin

-------------

Commit messages:
 - Missed a ws
 - JALR

Changes: https://git.openjdk.org/jdk/pull/18942/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18942&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8326306
  Stats: 362 lines in 9 files changed: 104 ins; 106 del; 152 mod
  Patch: https://git.openjdk.org/jdk/pull/18942.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18942/head:pull/18942

PR: https://git.openjdk.org/jdk/pull/18942