Remove .previous, .popsection configure tests

[Florian Weimer]

* Joseph Myers:

> 2015-10-15  Joseph Myers  <joseph@codesourcery.com>
>
> 	* configure.ac (libc_cv_asm_previous_directive): Remove configure
> 	test.
> 	(libc_cv_asm_popsection_directive): Likewise.
> 	* configure: Regenerated.
> 	* config.h.in (HAVE_ASM_PREVIOUS_DIRECTIVE): Remove #undef.
> 	(HAVE_ASM_POPSECTION_DIRECTIVE): Likewise.
> 	* include/libc-symbols.h [HAVE_ASM_PREVIOUS_DIRECTIVE]
> 	(__make_section_unallocated): Make definition unconditional.
> 	[HAVE_ASM_POPSECTION_DIRECTIVE] (__make_section_unallocated):
> 	Remove conditional definition.
> 	[!HAVE_ASM_PREVIOUS_DIRECTIVE && !HAVE_ASM_POPSECTION_DIRECTIVE]
> 	(__make_section_unallocated): Likewise.

Looks good.

Thanks,
Florian