Fix ldbl-96 remquol (finite, Inf) (bug 18244).

Fix ldbl-96 remquol (finite, Inf) (bug 18244).

ldbl-96 remquol wrongly handles the case where the first argument is
finite and the second infinite, because the check for the second
argument being a NaN fails to disregard the explicit high mantissa bit
and so wrongly interprets an infinity as being a NaN.  This patch
fixes this by masking off that bit, and improves test coverage for
both remainder and remquo (various cases were missing tests, or, as in
the case of the bug, were tested only for one of the two functions).

Tested for x86_64 and x86.

	[BZ #18244]
	* sysdeps/ieee754/ldbl-96/s_remquol.c (__remquol): Ignore explicit
	high mantissa bit when testing whether P is a NaN.
	* math/libm-test.inc (remainder_test_data): Add more tests.
	(remquo_test_data): Likewise.