FindPkgConfig: Write variables to cache for newer versions of pkg-config

This affects the FindPkgConfig module.

There is a bug when newer versions of pkg-config are installed which causes the variables ${_prefix}_INCLUDE_DIRS and ${_prefix}_CFLAGS_OTHER to only get set in the current scope and not written to the cache. Subsequent runs of CMake would cause the variables to not be set and the build to fail.

For instance running Ubuntu 22.04 (version 0.29.2 of pkg-config) works as expected but running Ubuntu 23.04 (version 1.8.1) breaks.

Issue: #25377 (closed)
Topic-rename: FindPkgConfig-caching

These results are intentionally not cached. Please see this documentation on find module result variables.

Please open an issue to describe the problem you're trying to solve.

closed

mentioned in issue #25377 (closed)

mentioned in merge request !9109 (merged)

reopened

changed the description

added workflow:in-review label

Closing in favor of !9109 (merged) which subsumes this fix.

closed

removed workflow:in-review label

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