Remove system_requirements exception for libusb

[Croydon]

I would like to create a "virtual package" for libudev in CCI, which relies on system_requirements to install libudev

The rational for whitelisting it in the first place was because @uilianries and I deemed it to be too low-level. Libudev is part of systemd, but I'm not sure how entangled it is with the rest of systemd

Libusb is currently installing libudev via system_requirements.

Moving it into an own recipe allows

• that other recipes can use it too
• if we ever decide to build it ourselves we can "just" replace the logic within the recipe

In general, I still firmly believe that system_requirements should be avoided so we should be careful when whitelisting stuff.

// @SSE4

Blocked by conan-io/conan-center-index#7940

[uilianries]

@czoido it's another example related to conan-io/conan-center-index#641

[jgsogo]

Link: conan-io/conan-center-index#2468

[Croydon]

I will update this to remove exception for libusb

All system "versions" are allowed by the hooks anyway

[Croydon]

This should only get merged after we actually have a system package including libudev, so that the libusb recipe can be updated accordingly

[Croydon]

Due to the merge of the default branch, this would now also remove the exception for the backward-cpp recipe. Are we okay with this?

[uilianries]

Due to the merge of the default branch, this would now also remove the exception for the backward-cpp recipe. Are we okay with this?

Okay