PATCH [perl #121257] blead fails at run/locale.t

Commit 65ebb05984db179833ff252f547043f32184d893changed the locale
initialization code to look at the LANG environment variable as a
fallback if there was a problem with a higher priority variable.

Thus, when trying to have an empty environment for testing, one now
needs to cause LANG to be unset, which wasn't the case before..This
commit adds that unset to the test that needs an empty environment.