Add more tests of libm functions.

Add more tests of libm functions.

This patch adds more randomly-generated tests of various libm
functions that are observed to increase ulps on x86_64.

Tested for x86_64 and x86 and ulps updated accordingly.

	* math/auto-libm-test-in: Add more tests of atan, clog, clog10,
	cos, csqrt, erf, erfc, exp2, lgamma, log1p, sin, sincos, tanh and
	tgamma.
	* math/auto-libm-test-out: Regenerated.
	* sysdeps/i386/fpu/libm-test-ulps: Update.
	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.