Fix hashing in Logging source gen

[tarekgh]

Fixes #110698

This change to avoid throwing from the hashing method which can break logging source generation.

I'll submit another PR to fix https://github.com/dotnet/extensions/blob/20c12ef61fc33865f36c1f4f6e8e2240e8c25f32/src/Generators/Microsoft.Gen.Logging/Emission/Emitter.Method.cs#L149 after I merge this one.

[tarekgh]

@stephentoub could you please help review this change. I recall you helped review the original code.

CC @geeknoid

[geeknoid]

Is this code supposed to actually be compiled with overflow checking on?

[tarekgh]

Is this code supposed to actually be compiled with overflow checking on?

My understanding is that overflowing check is turned on by default and we don't turn it off anywhere.

I misspoke here. Actually, the default behavior is unchecked according to the docs https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/statements/checked-and-unchecked#default-overflow-checking-context. I'll remove the use of unchecked in the change then. We still need the remaining changes

[geeknoid]

Ah, it's Math.Abs that's throwing the exception. Two's complement strikes again!