fix(linux): use $XDG_RUNTIME_DIR on GNU/Linux
fix(linux): use $XDG_RUNTIME_DIR on GNU/Linux

Some systems mount `/tmp` with `noexec`, causing `spawn EACCES` errors.

See: https://github.com/resin-io/etcher/issues/1699
See: https://specifications.freedesktop.org/basedir-spec/latest/ar01s03.html
Change-Type: patch
Changelog-Entry: Store GNU/Linux temporary scripts in `$XDG_RUNTIME_DIR`.
Signed-off-by: Juan Cruz Viotti <ee759b1936af4d7bd0d0e5363e6b1ea438e6a390@jviotti.com>

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