[PATCH] Use TEST_COMPARE_STRING in recently added test

[Gabriel F. T. Gomes]

On Wed, 07 Nov 2018, Florian Weimer wrote:

>* Gabriel F. T. Gomes:
>
>> 	* argp/tst-ldbl-argp.c (do_one_test): Use TEST_COMPARE_STRING,
>> 	instead of manually comparing and reporting mismatching strings.
>> 	* misc/tst-ldbl-error.c (do_one_test): Likewise.
>> 	* misc/tst-ldbl-warn.c (do_one_test): Likewise.  
>
>Patch looks okay to me.  Thanks.

Thanks.  Now committed.