Support for work without pkg-config for FindUUID

[osrf-migration]

Original report (archived issue) by Silvio Traversaro (Bitbucket: traversaro).

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Summary

Add code to permit to FindUUID to work even without pkg-config installed in the system.

Motivation

At the moment the FindUUID CMake scripts assume that pkg-config is installed in the system to work. This is a reasonable assumption, as FindUUID is supposed to work only on *nix systems. However, unfortunately the vcpkg continuous integration on Linux does not have/require pkg-config installed, and so the stock FindUUID fails on that machine, see microsoft/vcpkg#8044 (comment) . For this reason, it may be convient to support this case.

Describe alternatives you've considered

Leave the patch just in the vcpkg port: as in almost all other cases pkg-config will be installed, it make sense that the burden of maintenance of this case remains on the vcpkg side.

Additional context

The patch is already available in vcpkg at https://github.com/microsoft/vcpkg/pull/8044/files#diff-d3ef7f499fd629bfd6d5029bf3847dea , but I am not sure if it is of general interest, so I will open a PR only if there is interest.

[osrf-migration]

Original comment by Silvio Traversaro (Bitbucket: traversaro).

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• Edited issue description

[osrf-migration]

Original comment by Silvio Traversaro (Bitbucket: traversaro).

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• Edited issue description

[osrf-migration]

Original comment by Silvio Traversaro (Bitbucket: traversaro).

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• Edited issue description

[traversaro]

Clearly when packaging ignition-cmake2 for vcpkg ( microsoft/vcpkg#10014 ) I had completely forgot this patch, and now the dependent ports are not finding uuid .

[traversaro]

This was fixed in #95, so we can close the issue.