gdb/

gdb/
	Code cleanup for the next patch.
	* arm-linux-nat.c (arm_linux_stopped_data_address): Change variable
	siginfo_p to siginfo, update its users incl. the linux_nat_get_siginfo
	call for it.
	* ia64-linux-nat.c (ia64_linux_stopped_data_address): Likewise.
	(ia64_linux_stopped_data_address):
	* linux-nat.c (linux_nat_get_siginfo): Add parameter siginfo, change
	the return value.
	* linux-nat.h (linux_nat_get_siginfo): Likewise.
	* ppc-linux-nat.c (ppc_linux_stopped_data_address): Change variable
	siginfo_p to siginfo, update its users incl. the linux_nat_get_siginfo
	call for it.