Packages for the Linux perf profiler

This package provides the perf Linux profiler, which interfaces with the kernel perf events subsystem and tracing features. See https://perf.wiki.kernel.org/ for details.

Using perf requires a kernel with CONFIG_PERF_EVENTS enabled, not enabled on the default reMarkable kernel. Use the linux-mainline package, for example.

@matteodelabre did you test on a rM2 with linux-mainline? If so, this can probably be merged.

Since this package is built from @alistair23’s sources, I think it makes more sense to move this as a split package inside the existing linux-mainline recipe. It will ensure we keep both in sync.

Tested on rM2 (2.15.1.1189) with linux-mainline (6.0.0) and linux-stracciatella (5.4.70).

@matteodelabre I don't think this was waiting on anything further, right? Was this fully tested? I'm good to merge it if it's good to go.

Oh, looks like the build is broken when fetching sources.