Properly fix memory leak in _nss_dns_gethostbyname4_r with big DNS answer

Instead of trying to guess whether the second buffer needs to be freed
set a flag at the place it is allocated
Move tests of clog10 from libm-test.inc to auto-libm-test-in.

This patch moves tests of clog10 to auto-libm-test-in.  Note that this
means gen-auto-libm-tests will now depend on the recent MPC 1.0.2
release which added a fix for a bug that made gen-auto-libm-tests hang
for clog10.  (It still can't conveniently be used for cacos cacosh
casin casinh catan catanh csin csinh because of extreme slowness of
those functions for special cases in MPC; at least some slow cases of
csin / csinh are fixed in MPC trunk, but not in a release.)

Tested x86_64 and x86 and ulps updated accordingly.

	* math/auto-libm-test-in: Add tests of clog10.
	* math/auto-libm-test-out: Regenerated.
	* math/libm-test.inc (clog10_test_data): Use AUTO_TESTS_c_c.
	* sysdeps/i386/fpu/libm-test-ulps: Update.
	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.