superenv: prioritize dependencies' opt_lib in Linux rpath

[cho-m]

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From discussion in Homebrew/homebrew-core#99630 to avoid issues when trying to prioritize keg_only linkage for "drop-in" libraries (e.g. libpq, luajit-openresty, jpeg-turbo, ...)

Didn't see anyone open PR for it yet. Can discuss further if there are any odd scenarios to consider.

Will still require new bottles to update problematic RPATHs.

[BrewTestBot]

Review period will end on 2022-05-05 at 06:36:46 UTC.

[carlocab]

Thanks, @cho-m!

[BrewTestBot]

Review period ended.