gdb/

gdb/
	Support resolution of STT_GNU_IFUNC via breakpoints.
	* breakpoint.c (print_it_typical): Support bp_gnu_ifunc_resolver and
	bp_gnu_ifunc_resolver_return.
	(bpstat_what): Rename parameter to bs_head, new variable bs, adjust
	the loop.  Support bp_gnu_ifunc_resolver and
	bp_gnu_ifunc_resolver_return.  New comment after the loop.  New loop
	for bp_gnu_ifunc_resolver and bp_gnu_ifunc_resolver_return
	breakpoints.
	(bptype_string, print_one_breakpoint_location): Support
	bp_gnu_ifunc_resolver and bp_gnu_ifunc_resolver_return.
	(user_settable_breakpoint): Return true also for
	bp_gnu_ifunc_resolver.
	(allocate_bp_location): Support bp_gnu_ifunc_resolver and
	bp_gnu_ifunc_resolver_return.
	(set_breakpoint_location_function): New parameter explicit_loc,
	describe it.  Call find_pc_partial_function_gnu_ifunc with new
	variable IS_GNU_IFUNC and adjust the address for STT_GNU_IFUNC if
	EXPLICIT_LOC is not set.
	(set_raw_breakpoint): Set EXPLICIT_LOC for
	set_breakpoint_location_function.
	(clone_momentary_breakpoint): Use true for EXPLICIT_LOC of
	set_breakpoint_location_function.
	(mention): Support bp_gnu_ifunc_resolver and
	bp_gnu_ifunc_resolver_return.
	(add_location_to_breakpoint): Set EXPLICIT_LOC for
	set_breakpoint_location_function.
	(update_breakpoint_locations): Remove static.
	(breakpoint_re_set_one): Support bp_gnu_ifunc_resolver and
	bp_gnu_ifunc_resolver_return.
	* breakpoint.h (enum bptype): New fields bp_gnu_ifunc_resolver and
	bp_gnu_ifunc_resolver_return.
	(update_breakpoint_locations): New declaration.
	* elfread.c: Include gdbthread.h and regcache.h.
	(elf_gnu_ifunc_resolver_stop, elf_gnu_ifunc_resolver_return_stop): New
	functions.
	(elf_gnu_ifunc_fns): Install them.
	* minsyms.c (stub_gnu_ifunc_resolver_stop)
	(stub_gnu_ifunc_resolver_return_stop): New functions.
	(stub_gnu_ifunc_fns): Install them.
	* symtab.h (struct gnu_ifunc_fns): New fields gnu_ifunc_resolver_stop
	and gnu_ifunc_resolver_return_stop.
	(gnu_ifunc_resolver_stop, gnu_ifunc_resolver_return_stop): New.