x86; Allow IFUNC pointer defined in PDE

If IFUNC symbol is defined in position-dependent executable, we should
change it to the normal function and set its address to its PLT entry
which should be resolved by R_*_IRELATIVE at run-time.  All external
references should be resolved to its PLT in executable.

bfd/

	PR ld/23169
	* elf-ifunc.c (_bfd_elf_allocate_ifunc_dyn_relocs): Don't issue
	an error on IFUNC pointer defined in PDE.
	* elf32-i386.c (elf_i386_finish_dynamic_symbol): Call
	_bfd_x86_elf_link_fixup_ifunc_symbol.
	* elf64-x86-64.c (elf_x86_64_finish_dynamic_symbol): Likewise.
	* elfxx-x86.c (_bfd_x86_elf_link_fixup_ifunc_symbol): New
	function.
	* elfxx-x86.h (_bfd_x86_elf_link_fixup_ifunc_symbol): New.

ld/

	PR ld/23169
	* testsuite/ld-ifunc/ifunc-9-i386.d: New file.
	* testsuite/ld-ifunc/ifunc-9-x86-64.d: Likewise.
	* testsuite/ld-ifunc/pr23169a.c: Likewise.
	* testsuite/ld-ifunc/pr23169a.rd: Likewise.
	* testsuite/ld-ifunc/pr23169b.c: Likewise.
	* testsuite/ld-ifunc/pr23169b.c: Likewise.
	* testsuite/ld-ifunc/pr23169c.rd: Likewise.
	* testsuite/ld-ifunc/pr23169c.rd: Likewise.
	* testsuite/ld-ifunc/ifunc-9-x86.d: Removed.
	* testsuite/ld-ifunc/ifunc.exp: Run PR ld/23169 tests.