[m-rev.] diff: expect hard_coded/write_float_special to fail

[Zoltan Somogyi]

The diff is to add hard_coded/write_float_special to tests/
EXPECT_FAIL_TESTS.all_grades.

Julien, when you make the fix you said you were working on
to standardize the formatting of nans and infs, please undo this.

Zoltan.