Add If statement benchmarks

[a74nh]

No description provided.

[a74nh]

These tests are added to test the if conversion pass being added here: dotnet/runtime#67894

The performance of csel vs a branch is dependant on the frequency of the branches being taken or not. If the closer to a 50/50 split then the faster csel will perform. As the branch choices gets closer to always taken or always not taken, then using branches becomes faster.

Therefore for the simple case, I've used a %2 test to approximate 50/50.

For the other cases, getting to 50/50 isn't quite so simple. Keeping with %2 seemed the best approach.

[a74nh]

Some performance diffs when using csel instructions: dotnet/runtime#67894 (comment)

[kunalspathak]

LGTM

[danmoseley]

@kunalspathak should we merge then?

[kunalspathak]

Sure, I am not sure if centos 7 failures are known, but otherwise, we can merge it.

[danmoseley]

Yes they are known.

[danmoseley]

Thanks @a74nh sorry for overlooking this.