libevent: build either shared or static

[SpaceIm]

Specify library name and version: lib/1.0

This is also a good place to share with all of us why you are submitting this PR (specially if it is a new addition to ConanCenter): is it a dependency of other libraries you want to package? Are you the author of the library? Thanks!

---

• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
• I've used the latest Conan client version.
• I've tried at least one configuration locally with the conan-center hook activated.

[conan-center-bot]

All green in build 1 (63bc0dba7018cc421513e7c104586bdfbe0d9661):

• libevent/2.1.12@:
  All packages built successfully! (All logs)

• libevent/2.1.11@:
  All packages built successfully! (All logs)

[uilianries]

LGTM

[SpaceIm]

FYI, the issue was reported on slack: https://cpplang.slack.com/archives/C41CWV9HA/p1666088803439519. tc.variables doesn't seem to override values of variables defined as CACHE variables in upstream CMakeLists (see conan-io/conan#11937 if you want more explanation): https://github.com/libevent/libevent/blob/8f47d8de281b877450474734594fdc0a60ee35d1/CMakeLists.txt#L42-L43

[prince-chrismc]

One more thing to look at when we review 🙈