Unit test for locale fails for some locales on macOS for negative dates

When running unit test tst_QLocale on macOS on a computer with Norwegian locale the test dateFormat fails. This because the last test checks for (hyphen) U+002d but the generated string uses U+2212 as a negative sign.

The current implementation gives the following output:

FAIL!  : tst_QLocale::dateFormat() 'old.contains(u"-1173")' returned FALSE. (1. mai −1173 for locale nb_NO)
   Loc: [/Users/oyheskes/src/qt-doc/qtbase/tests/auto/corelib/text/qlocale/tst_qlocale.cpp(2792)]