JIT: Optimize simple MUL/DIV arithmetic with GT_NEG

[JulieLeeMSFT]

This is part 2 of #13837 to optimize multiplication and division arithmetic optimizations with GT_NEG.
Addition and subtraction have been completed in PR #43921.

int M5(int a) =>  -a / 10;  // optimize to  "a / -10"
int M6(int a) => -(a / 10); // optimize to  "a / -10"
int M7(int a) =>  -a * 10;  // optimize to  "a * -10"
int M8(int a) => -(a * 10); // optimize to  "a * -10"

category:cq
theme:basic-cq
skill-level:beginner
cost:small

[EgorBo]

A small note: 10 -> -10 should not be done for IconHandle constant (#44266)

[alexcovington]

@JulieLeeMSFT This seems like a good introductory issue to get familiar with the JIT, which I've been looking for. Would you be able to assign this to me?

[danmoseley]

@alexcovington is this issue now completed? If so we can close it.

perhaps there's another issue that's interesting among our codegen issues up for grabs: https://github.com/dotnet/runtime/issues?q=is%3Aopen+label%3Aup-for-grabs+label%3Aarea-CodeGen-coreclr+

[alexcovington]

@danmosemsft Yes, I believe this can be closed now that #45604 has been merged in.

And I'll gladly take a look through 😄. Feel free to ping me for AMD-specific or x64 issues (I saw the amd-perf label which I'm following).

[danmoseley]

@alexcovington great, we would be excited to have more of your contributions in .NET 6.0.
cc @BruceForstall in case he has specific interesting suggestions.