Fix build on macOS.

[brndnmtthws]

The prototypes for cgsleep_ms_r and cgsleep_us_r didn't match the
implementation, and have been updated accordingly.

There's something weird about these functions returning a value, since most of them were void but a couple were returning ints. My guess is that someone needed to debug something and added the code, but never updated the other functions. For the sake of backward compatibility I just added return 0 to the versions returning void.

[jameshilliard]

FYI anything inside USE_BITMAIN_SOC will never be used on macOS as the bitmain soc driver is strictly linux only.

[jameshilliard]

I had to ifdef the timing code for that driver since a bisect revealed the newer changes(the timing code not inside USE_BITMAIN_SOC) was causing that driver to fail.

[brndnmtthws]

@jameshilliard I don't quite understand why the function signatures need to be different. It doesn't make much difference to me in either case.

[jameshilliard]

Yeah, it may not have been the function signatures that was the issue, I'll try and test these changes when I get some time to verify they don't introduce a regression there.

[metebalci]

This is also an issue for Windows cross compile.