Locale-dependent test failures

[eserte]

With non-English locales (and probably only for older perls, approx. < 5.22) the t/03-parsing-errors.t test fails:

    #   Failed test 'threw Regexp ((?^:failed on t/data/errors/nonexistent.err: No such file or directory))'
    #   at t/03-parsing-errors.t line 27.
    # expecting: Regexp ((?^:failed on t/data/errors/nonexistent.err: No such file or directory))
    # found: parse failed on t/data/errors/nonexistent.err: Datei oder Verzeichnis nicht gefunden at (eval 40) line 1.
    # Looks like you failed 1 test of 1.

#   Failed test 'nonexistent'
#   at t/03-parsing-errors.t line 29.
# Looks like you failed 1 test of 3.
t/03-parsing-errors.t ........ 
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/3 subtests 

[robrwo]

These are now skipped when the locale is non-English, but ideally we'd want to come up with a locale-independent means of testing them.