compliance: #27 tentative tests for scalar instructions.

- Includes fix to RV32 SAIL model for sha512 instructions.

- Shortcomings:

  - No coverage numbers (yet). Need help from Imperas?

  - Same source/dest registers used every time. This can be fixed
    easily though.

- Generated tests for all RV32 and RV64 scalar ISA instructions.

- KAT values use Spike as the golden reference.

- SAIL CSIM and OCAML simulators agree with spike.

- Update the riscv-compliance patch with reference output values.

 On branch dev/next-release
 Your branch is ahead of 'origin/dev/next-release' by 1 commit.
   (use "git push" to publish your local commits)

 Changes to be committed:
	modified:   sail/riscv_insts_crypto_rv32.sail
	modified:   tests/compliance/Makefile
	modified:   tests/compliance/README.md
	new file:   tests/compliance/generate_tests.py
	modified:   tests/compliance/riscv-compliance.patch
	new file:   tests/compliance/test_template.S

 Changes not staged for commit:
	modified:   extern/riscv-compliance (modified content)
	modified:   extern/riscv-gnu-toolchain (modified content, untracked content)
	modified:   extern/riscv-isa-sim (modified content)
	modified:   extern/sail-riscv (modified content, untracked content)