Add more libm tests (scalb*, signbit, sin, sincos, sinh, sqrt, tan, tanh, tgamma...

Add more libm tests (scalb*, signbit, sin, sincos, sinh, sqrt, tan, tanh, tgamma, y0, y1, yn, significand).

This patch improves the libm test coverage for a few more functions.

Tested for x86_64 and x86.

	* math/auto-libm-test-in: Add more tests of sin, sincos, sinh,
	sqrt, tan, tanh, y0, y1 and yn.
	* math/auto-libm-test-out: Regenerated.
	* math/libm-test.inc (scalb_test_data): Add more tests.
	(scalbn_test_data): Likewise.
	(scalbln_test_data): Likewise.
	(signbit_test_data): Likewise.
	(sin_test_data): Likewise.
	(sincos_test_data): Likewise.
	(sinh_test_data): Likewise.
	(sqrt_test_data): Likewise.
	(tan_test_data): Likewise.
	(tanh_test_data): Likewise.
	(tgamma_test_data): Likewise.
	(y0_test_data): Likewise.
	(y1_test_data): Likewise.
	(yn_test_data): Likewise.
	(significand_test_data): Likewise.
	* sysdeps/i386/fpu/libm-test-ulps: Update.