MinGW: disable legacy encoding tests
On Windows, all native APIs are Unicode-based. It is impossible to pass
legacy encoded byte arrays to a process via command line or environment
variables. Disable the tests that try to do so.
In t3901, most tests still work if we don't mess up the repository encoding
in setup, so don't switch to ISO-8859-1 on MinGW.
Note that i18n tests that do their encoding tricks via encoded files (such
as t3900) are not affected by this.
Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Stepan Kasal <kasal@ucw.cz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>