Add lib64 path as default path for plugins

[ycollet]

On fedora and on some others distro, ladspa, dssi and lv2 plugins are located in:

• /usr/lib64/dssi
• /usr/lib64/ladspa
• /usr/lib64/lv2

Add these paths as default path in the preferences.

[falkTX]

Carla uses <...> _ PATH as default, like LADSPA_PATH, LV2_PATH etc.
If your distro sets up these, Carla will pick it up.

The issue here is that Debian&Ubuntu might have /usr/lib64, but it will be a symlink to /usr/lib, which results in duplicated plugins.

[eeickmeyer]

Looks like this is still unresolved. Either way, I might make a default config for Fedora Jam to set those paths, as I believe Fedora doesn't set those paths by default. In fact, I don't believe Ubuntu does either.

[uhtzmann]

(Copy from #1431 (comment).)

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I see that Carla has /usr/lib64 listed in Settings -> Configure Carla -> Plugin Paths in my Fedora 35 install.

This is also the case after removing existing configs from ~/.config/falkTX and letting new ones be created from defaults.

Can it be confirmed that this issue is still present for somebody?