t0001 (mingw): do not expect a specific order of stdout/stderr

t0001 (mingw): do not expect a specific order of stdout/stderr

When redirecting stdout/stderr to the same file, we cannot guarantee
that stdout will come first.

In fact, in this test case, it seems that an MSVC build always prints
stderr first.

In any case, this test case does not want to verify the *order* but
the *presence* of both outputs, so let's test exactly that.

Signed-off-by: Johannes Schindelin <redacted>
Signed-off-by: Junio C Hamano <redacted>