Fix double to float conversion warnings in virtual gamepad logic

[StephenCWills]

Fixes these warnings, highlighted by GitHub's nifty beta feature.

[StephenCWills]

Weird quirk about g++ and cmath.
https://stackoverflow.com/a/43183942

g++ 5.x though 7, sqrtf and floorf are not within the std namespace under -std=c++11, -std=c++14 or -std=c++1z. They are simply in the global namespace, when cmath is included.

I assume we're using a later version of the compiler, but the info seems to be still relevant.