libudev: Set the pkg-config version to the real version number

[jwillikers]

The pkg-config file contains the version of the Conan package. This is problematic because it is system which causes version checks for libudev to fail. This happens in Weston I'm making for instance:

Dependency libudev found: NO found system but need: '>= 136'
Found CMake: /usr/local/bin/cmake (3.28.20240202)
Run-time dependency libudev found: NO (tried cmake)

../src/libweston/meson.build:196:2: ERROR: Dependency lookup for libudev with method 'pkgconfig' failed: Invalid version, need 'libudev' ['>= 136'] found 'system'.

I've set the version in the pkg-config file to that of the version on the system. This fixes version checks in consumers using pkg-config.

[conan-center-bot]

Conan v1 pipeline ✔️

All green in build 1 (72b9f7c1e377713d63fb566496d995467d780539):

• libudev/system:
  All packages built successfully! (All logs)

---

Conan v2 pipeline ✔️

Note: Conan v2 builds are now mandatory. Please read our discussion about it.

All green in build 1 (72b9f7c1e377713d63fb566496d995467d780539):

• libudev/system:
  All packages built successfully! (All logs)

[uilianries]

Hello @jwillikers Could you please share your entire build log? Please, try to follow the bug package template when sending hotfix without an issue associate, so we can reproduce your error quickly, without asking for extra information.

[jwillikers]

Hello @jwillikers Could you please share your entire build log? Please, try to follow the bug package template when sending hotfix without an issue associate, so we can reproduce your error quickly, without asking for extra information.

@uilianries This currently effects two unmerged PR's: #20358 and #22938. To reproduce the one for libweston, which I placed above, you'd need to build multiple dependencies which haven't been merged like Mesa and PipeWire, and there'd be a lot of dependency version conflicts getting in the way as well. The build logs I've included contain all the pertinent information for the error. It's probably easier to look at the code here to understand what is happening:

	dependencies: [
		dep_libweston_private,
		dep_libinput,
		dependency('libudev', version: '>= 136')
	],

The dependency directive in Meson looks for a version of libudev that is greater than or equal to 136. It doesn't find it because libudev/system uses system as the version instead of a number, which results in the failure as the log above says. To reproduce, it's simple enough to look at the generated libudev.pc file for the test package. Before this PR, the Version field says system. With this PR, you can see libudev.pc file has the correct Version field. If you want to reproduce with a package, I can work on updating the libgudev PR or can walk you through all of the dependencies that need to be built locally to reproduce with the weston PR.

[uilianries]

@jwillikers Thank your for the details, now I see your scenario!

[uilianries]

LGTM. The follow-up clarifies this fix.