gdb/

gdb/
	STT_GNU_IFUNC reader implementation.
	* elfread.c: Include gdbtypes.h, value.h and infcall.h.
	(SYMBOL_GOT_PLT_SUFFIX, elf_rel_plt_read)
	(elf_objfile_gnu_ifunc_cache_data, struct elf_gnu_ifunc_cache)
	(elf_gnu_ifunc_cache_hash, elf_gnu_ifunc_cache_eq)
	(elf_gnu_ifunc_record_cache, elf_gnu_ifunc_resolve_by_cache)
	(elf_gnu_ifunc_resolve_by_got, elf_gnu_ifunc_resolve_name)
	(elf_gnu_ifunc_resolve_addr): New.
	(elf_symfile_read): Call elf_rel_plt_read.
	(elf_gnu_ifunc_fns): New.
	(_initialize_elfread): Initialize elf_objfile_gnu_ifunc_cache_data.
	Install elf_gnu_ifunc_fns.
	* infcall.c (find_function_return_type): New function.
	(find_function_addr): Resolve TYPE_GNU_IFUNC functions, if possible.
	* minsyms.c (stub_gnu_ifunc_resolve_addr)
	(stub_gnu_ifunc_resolve_name): New functions.
	(stub_gnu_ifunc_fns, gnu_ifunc_fns_p): New variables.
	* symtab.h (struct gnu_ifunc_fns, gnu_ifunc_resolve_addr)
	(gnu_ifunc_resolve_name, gnu_ifunc_fns_p): New.