gdb/linux-record: Remove size_siginfo

gdb/linux-record: Remove size_siginfo

It's a duplicate of size_siginfo_t.

gdb/ChangeLog:

	* aarch64-linux-tdep.c (aarch64_linux_init_abi): Remove size_siginfo.
	* amd64-linux-tdep.c (amd64_linux_init_abi): Remove size_siginfo.
	(amd64_x32_linux_init_abi): Remove size_siginfo.
	* arm-linux-tdep.c (arm_linux_init_abi): Remove size_siginfo.
	* i386-linux-tdep.c (i386_linux_init_abi): Remove size_siginfo.
	* linux-record.c (record_linux_system_call): Change size_siginfo
	to size_siginfo_t.
	* linux-record.h (struct linux_record_tdep): Remove size_siginfo.
	* ppc-linux-tdep.c (ppc_init_linux_record_tdep): Remove size_siginfo.