Further performance improvements for FP math

[heshpdx]

I was requested to dig further in the spirit of !852 so I spent time inspecting other parts of the code. This PR unlocks more FDIV->FMUL opportunities. I inspected the assembly and confirmed that each of the changes did result in a transformation of FDIV to FMUL.

Here are the perf outliers, with the majority of other tests in the noise (since likely they do not exercise the changed code).

Grid path cells shows 4.3% upside, as measured on a Ampere Altra in the OCI Cloud, using gcc-10 out of the box. Regular h3 cmake build.
mainline:

$ ./build/bin/benchmarkGridPathCells 
        -- gridPathCellsNear: 39.136827 microseconds per iteration (10000 iterations)
        -- gridPathCellsFar: 1799.592192 microseconds per iteration (1000 iterations)

branch:

$ ./build_fast/bin/benchmarkGridPathCells 
        -- gridPathCellsNear: 37.556445 microseconds per iteration (10000 iterations)
        -- gridPathCellsFar: 1724.603344 microseconds per iteration (1000 iterations)

The experimental polygon to cells overlapping is also an outlier, 1-2%:

mainline:

        -- polygonToCellsSF_Overlapping: 5817.474534 microseconds per iteration (500 iterations)
        -- polygonToCellsAlameda_Overlapping: 13169.533630 microseconds per iteration (500 iterations)
        -- polygonToCellsSouthernExpansion_Overlapping: 381815.775600 microseconds per iteration (10 iterations)

branch:

        -- polygonToCellsSF_Overlapping: 5773.028512 microseconds per iteration (500 iterations)
        -- polygonToCellsAlameda_Overlapping: 12886.969474 microseconds per iteration (500 iterations)
        -- polygonToCellsSouthernExpansion_Overlapping: 377545.843300 microseconds per iteration (10 iterations)

[coveralls]

coverage: 98.824% (-0.002%) from 98.826%
when pulling b7542c3 on heshpdx:master
into a1037eb on uber:master.

[nrabinowitz]

Thanks for these optimizations!

[heshpdx]

Looks like the CIFuzz is broken. Do we need to update that runner?

[isaacbrodsky]

Looks like the CIFuzz is broken. Do we need to update that runner?

I'm addressing it in #907. You may need to rebase or merge that change in too