aarch64: Fix gcc.target/aarch64/sve/pcs failures

aarch64: Fix gcc.target/aarch64/sve/pcs failures

Several gcc.target/aarch64/sve/pcs tests started failing after
6a2e8dcbbd4, because the tests weren't robust against whether
an indirect argument register or the stack pointer was used as
the base for stores.

The patch allows either base register when there is only one
indirect argument.  It disables -fcprop-registers in cases where
there are sometimes multiple indirect arguments, since the name
of the argument register is then an important part of the test.

Disabling -fcprop-registers gives poor final register allocation,
since:

* combine's make_more_copies hack adds extra redundant moves
* code with those moves is not allocated as well as moves without them
* we often rely on -fcprop-registers to clean up the allocation later

The patch therefore disables combine in the same tests as
cprop-registers.

gcc/testsuite/
	* gcc.target/aarch64/sve/pcs/args_1.c: Match moves from the stack
	pointer to indirect argument registers and allow either to be used
	as the base register in subsequent stores.
	* gcc.target/aarch64/sve/pcs/args_8.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_2.c: Allow the store of the
	indirect argument to happen via the argument register or the
	stack pointer.
	* gcc.target/aarch64/sve/pcs/args_3.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_4.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_be_bf16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_be_f16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_be_f32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_be_f64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_be_s16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_be_s32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_be_s64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_be_s8.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_be_u16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_be_u32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_be_u64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_be_u8.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_le_bf16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_le_f16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_le_f32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_le_f64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_le_s16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_le_s32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_le_s64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_le_s8.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_le_u16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_le_u32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_le_u64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_5_le_u8.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_be_bf16.c: Disable
	-fcprop-registers and combine.
	* gcc.target/aarch64/sve/pcs/args_6_be_f16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_be_f32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_be_f64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_be_s16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_be_s32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_be_s64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_be_s8.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_be_u16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_be_u32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_be_u64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_be_u8.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_le_bf16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_le_f16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_le_f32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_le_f64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_le_s16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_le_s32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_le_s64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_le_s8.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_le_u16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_le_u32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_le_u64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/args_6_le_u8.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_1.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_2_f16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_2_f32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_2_f64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_2_s16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_2_s32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_2_s64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_2_s8.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_2_u16.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_2_u32.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_2_u64.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_2_u8.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_3_nosc.c: Likewise.
	* gcc.target/aarch64/sve/pcs/varargs_3_sc.c: Likewise.