Hotfix/vuv

[maddyscientist]

This hotfix fixes the performance of the VUV kernel:

• When two-stage tuning was enabled, it was observed that the VUV kernel seemingly regressed (#1291)
• It turns out this wasn't a regression per se, rather it revealed a long standing issue that the launch parameters of the VUV kernel weren't being set correctly outside of the tuning loop
• Specifically, the Arg::coarse_color_wave parameter, which maps to TuneParam::aux wasn't being set in the apply function, it was only being set during the tuning process.
• So while the kernel autotuned correctly, post tuning, it would not be using the desired parameters, leading to reduced performance.

I have also made some minor changes to the tuning:

• Display a warning if the best second-stage tuning time regresses by more than 10% versus the first stage. In general we should expect the second stage to be faster than the first stage, since it will generally involve more iterations. The 10% margin is left due to latency bubbles, etc.
• Even then, this warning can still be triggered if one doesn't lock clocks for small short running kernels.
• Fix a minor bug when printing the aux parameter while tuning.
• Replace use of new/delete with a std::vector

Closes #1291

[weinbe2]

Visual review looks great, I'm always a fan of a simple fix. I've got a due-diligence build+run going now, once that's complete I'll give it the approval + merge.