i386: Don't allow GOTOFF relocation against IFUNC symbol for PIC

We can't use the PLT entry as the function address for PIC since the PIC
register may not be set up properly for indirect call.

bfd/

	PR ld/27998
	* elf32-i386.c (elf_i386_relocate_section): Don't allow GOTOFF
	relocation against IFUNC symbol for PIC.

ld/

	PR ld/27998
	* testsuite/ld-i386/pr27998a.d: Replace -shared with -e bar.
	* testsuite/ld-i386/pr27998b.d: Expect a linker error.
	* testsuite/ld-ifunc/ifunc-2-i386-now.d: Updated.
	* testsuite/ld-ifunc/ifunc-2-local-i386-now.d: Likewise.
	* testsuite/ld-ifunc/ifunc-2-i386.s: Replace @GOTOFF with @GOT.
	* testsuite/ld-ifunc/ifunc-2-local-i386.s: Likewise.

(cherry picked from commit 8f29211c)