libraries/libfm-qt: Fix cmake compilation error

[isaackwy]

I had received the following compilation error:

CMake Error at CMakeLists.txt:1 (cmake_minimum_required):
  Compatibility with CMake < 3.5 has been removed from CMake.

  Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
  to tell CMake that the project requires at least <min> but has been updated
  to work with policies introduced by <max> or earlier.

  Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway.

Older programs tend to have this issue.

[github-actions]

reverse dependencies - libraries/libfm-qt

• libraries/lxqt-qtplugin

[github-actions]

✅ sbolint - libraries/libfm-qt ✅

libfm-qt: NOTE: libfm-qt.SlackBuild:61: LIBDIRSUFFIX gets set, but never used.
sbolint: libfm-qt checks out OK

[Ponce]

thanks, pushed in its own branch!