Remove configure tests for visibility support

[Florian Weimer]

On 10/29/2015 12:49 AM, Joseph Myers wrote:

> 2015-10-28  Joseph Myers  <joseph@codesourcery.com>
> 
> 	* configure.ac (libc_cv_asm_protected_directive): Remove configure
> 	test.
> 	(libc_cv_visibility_attribute): Likewise.
> 	(libc_cv_protected_data): Test unconditionally.
> 	(libc_cv_broken_visibility_attribute): Remove configure test.
> 	(libc_cv_have_sdata_section): Test unconditionally.
> 	* configure: Regenerated.

Looks good to me.

Florian