PR28523, ld.bfd created undefined symbols on ppc64

PR28523, ld.bfd created undefined symbols on ppc64

This patch removes any fake (linker created) function descriptor
symbol if its code entry symbol isn't dynamic, to ensure bogus dynamic
symbols are not created.  The change to func_desc_adjust requires that
it be run only once, which means ppc64_elf_tls_setup can't call it for
just a few selected symbols.

	PR 28523
	* elf64-ppc.c (func_desc_adjust): If a function entry sym is
	not dynamic and has no plt entry, hide any associated fake
	function descriptor symbol.
	(ppc64_elf_edit): Move func_desc_adjust iteration over syms to..
	(ppc64_elf_tls_setup): ..here.