Add catan, catanh tests at +/- 1 and +/- i.
math: Use accurate answers for cos and sincos.

Use the most accurate hex literals possible for the answers to the
cos and sincos tests that vary according to the error in the rounding
of PI/2.

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2013-04-24  Carlos O'Donell  <carlos@redhat.com>

	* math/libm-test.inc (cos_test): Use accurate hex constants.
	(sincost_test): Likewise.