[lldb/test] Disable NSDate format check under _WIN32
Disable the test which attempts to format an NSDate with a date_value of
0 on _WIN32.
When _WIN32 is defined, GetOSXEpoch returns a date that should be in
2001, but after this is passed through timegm (which, afaict isn't
portable?) the result is a date in 1970:
lldb-x64-windows-ninja\llvm-project\lldb\unittests\DataFormatter\MockTests.cpp(39): error: Expected: *formatDateValue(0) Which is: "1970-01-01 00:00:00 Pacific Standard Time" To be equal to: "2001-01-01 00:00:00 UTC"