aarch64: Fix an ICE in register_tuple_type [PR95523]

aarch64: Fix an ICE in register_tuple_type [PR95523]

When registering the tuple type in register_tuple_type, the
TYPE_ALIGN (tuple_type) will be changed by -fpack-struct=n. We need to
maintain natural alignment in handle_arm_sve_h.

2020-06-10  Haijian Zhang  <z.zhanghaijian@huawei.com>

gcc/
	PR target/95523
	* config/aarch64/aarch64-sve-builtins.h
	(sve_switcher::m_old_maximum_field_alignment): New member.
	* config/aarch64/aarch64-sve-builtins.cc
	(sve_switcher::sve_switcher): Save maximum_field_alignment in
	m_old_maximum_field_alignment and clear maximum_field_alignment.
	(sve_switcher::~sve_switcher): Restore maximum_field_alignment.

gcc/testsuite/
	PR target/95523
	* gcc.target/aarch64/sve/pr95523.c: New test.