This test applies to i386 and x86_64 which set R_386_GLOB_DAT and
R_X86_64_GLOB_DAT to ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA.
[BZ #19178]
* sysdeps/x86/Makefile (tests): Add tst-prelink.
(tst-prelink-ENV): New.
($(objpfx)tst-prelink-conflict.out): Likewise.
($(objpfx)tst-prelink-cmp.out): Likewise.
(tests-special): Add $(objpfx)tst-prelink-cmp.out.
* sysdeps/x86/tst-prelink.c: New file.
* sysdeps/x86/tst-prelink.exp: Likewise.