Use bindtextdomain() hack to reset cache

[hadley]

Per r-lib/withr#183, I think this should be adequate.

Let me know if you think I should construct a test that illustrates the problem and the fix.

[gaborcsardi]

This does not work for me on macOS CRAN R 4.1.1:

❯ pkgload::load_all()
ℹ Loading testTranslations

❯ hello()
[1] "Hello"

❯ Sys.setenv(LANGUAGE="fr")
❯ hello()
[1] "Bonjour"

# Now edit the `po/R-fr.po` file and run
# `msgfmt -c --statistics -o inst/po/fr/LC_MESSAGES/R-testTranslations.mo po/R-fr.po`

❯ pkgload::load_all()
ℹ Loading testTranslations

❯ hello()
[1] "Bonjour"

The translation is not updated.

As a sanity check, if I restart R, then of course the new translation is loaded:

❯ R -q -e 'pkgload::load_all(); Sys.setenv(LANGUAGE="fr"); hello()'
> pkgload::load_all(); Sys.setenv(LANGUAGE="fr"); hello()
ℹ Loading testTranslations
[1] "Salut"

[hadley]

Ok, I'll definitely construct a better test then.