Remove .previous, .popsection configure tests.

Remove .previous, .popsection configure tests.

There is a configure test for the assembler .previous directive, and,
as a fallback, for .popsection.

glibc now only supports ELF.  For ELF, the GNU assembler has supported
.previous since version 2.2 (support added by

Mon Jul 19 15:21:20 1993  Ken Raeburn  (raeburn@rtl.cygnus.com)

        * config/obj-elf.c (obj_elf_previous): New function.
        (previous_section, previous_subsection): New vars.
        (obj_elf_section): Save current place in case DWARF code wants us
        to pop back to it.  Handle unquoted section name as well as quoted
        section name.  Don't crash on invalid strings.
        (obj_pseudo_table): Handle new pseudos "previous", "2byte", and
        "4byte".

).  Thus this configure test is obsolete, and this patch removes it
(and with it the fallback .popsection test).

Tested for x86_64 and x86 (testsuite, and that installed shared
libraries are unchanged by the patch).

	* 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.