Move tests of cpow from libm-test.inc to auto-libm-test-in.

Move tests of cpow from libm-test.inc to auto-libm-test-in.

This patch moves tests of cpow to auto-libm-test-in, adding the
required support to gen-auto-libm-tests.

Tested x86_64 and x86 and ulps updated accordingly.

	* math/auto-libm-test-in: Add tests of cpow.
	* math/auto-libm-test-out: Regenerated.
	* math/libm-test.inc (cpow_test_data): Use AUTO_TESTS_cc_c.
	* * math/gen-auto-libm-tests.c (func_calc_method): Add value
	mpc_cc_c.
	(func_calc_desc): Add mpc_cc_c union field.
	(test_functions): Add cpow.
	(special_fill_2pi): New function.
	(special_real_inputs): Add 2pi.
	(calc_generic_results): Handle mpc_cc_c.
	* sysdeps/i386/fpu/libm-test-ulps: Update.
	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.