Pass ptid to to_prepare_to_store

Pass ptid to to_prepare_to_store

In the same vein as to_fetch_registers and to_store_registers, we can
update to_prepare_to_store to take the ptid of the thread whose register
we want to store as a parameter, rather than reading it from
inferior_ptid.

gdb/ChangeLog:

	* target.h (struct target_ops) <to_prepare_to_store>: Add ptid_t
	parameter.
	(target_prepare_to_store): Likewise.
	* target-delegates.c: Re-generate.
	* inf-child.c (inf_child_prepare_to_store): Add ptid parameter.
	* ppc-ravenscar-thread.c
	(ppc_ravenscar_generic_prepare_to_store): Likewise.
	* ravenscar-thread.c (ravenscar_prepare_to_store): Add ptid
	parameter and use it instead of inferior_ptid.
	* ravenscar-thread.h (struct ravenscar_arch_ops)
	<to_prepare_to_store>: Add ptid parameter.
	* record-btrace.c (record_btrace_prepare_to_store): Add ptid
	parameter and use it instead of inferior_ptid.
	* record-full.c (record_full_core_prepare_to_store): Add ptid
	parameter.
	* regcache.c (regcache_raw_write): Pass ptid to
	target_prepare_to_store.
	* remote-sim.c (gdbsim_prepare_to_store): Add ptid parameter.
	* remote.c (remote_prepare_to_store): Add ptid parameter.
	* sparc-ravenscar-thread.c (sparc_ravenscar_prepare_to_store):
	Add ptid parameter.