Run tst-prelink test for GLOB_DAT reloc

Run tst-prelink test on targets with GLOB_DAT relocaton.

	* config.make.in (have-glob-dat-reloc): New.
	* configure.ac (libc_cv_has_glob_dat): New.  Set to yes if
	target supports GLOB_DAT relocaton. AC_SUBST.
	* configure: Regenerated.
	* elf/Makefile (tests): Add tst-prelink.
	(tests-special): Add $(objpfx)tst-prelink-cmp.out.
	(tst-prelink-ENV): New.
	($(objpfx)tst-prelink-conflict.out): Likewise.
	($(objpfx)tst-prelink-cmp.out): Likewise.
	* sysdeps/x86/tst-prelink.c: Moved to ...
	* elf/tst-prelink.c: Here.
	* sysdeps/x86/tst-prelink.exp: Moved to ...
	* elf/tst-prelink.exp: Here.
	* sysdeps/x86/Makefile (tests): Don't add tst-prelink.
	(tst-prelink-ENV): Removed.
	($(objpfx)tst-prelink-conflict.out): Likewise.
	($(objpfx)tst-prelink-cmp.out): Likewise.
	(tests-special): Don't add $(objpfx)tst-prelink-cmp.out.