Restrict checking value.lval on using address

Restrict checking value.lval on using address

With the previous change, value.location.address is only valid for
lval_memory.  This patch restrict some checking on value.lval on
using address.  Since we have a check on VALUE_VAL in
set_value_address, we need to set VALUE_VAL properly before
set_value_address too.

gdb:

2016-11-25  Yao Qi  <yao.qi@linaro.org>

	* ada-lang.c (ensure_lval): Call set_value_address after setting
	VALUE_LVAL.
	* elfread.c (elf_gnu_ifunc_resolve_addr): Set VALUE_LVAL to
	lval_memory.
	(elf_gnu_ifunc_resolver_return_stop): Likewise.
	* value.c (value_fn_field): Likewise.
	(value_from_contents_and_address_unresolved): Likewise.
	(value_from_contents_and_address): Likewise.
	(value_address): Check value->lval isn't
	lval_memory.
	(value_raw_address): Likewise.
	(set_value_address): Assert value->lval is lval_memory.