RISC-V: Fix LRA issue for LMUL < 1 vector spillings [PR109244]

In order to decrease the memory traffic, we don't use whole register
load/store for the LMUL less than 1 and mask mode, so those case will
require one extra general purpose register for setting up VL register,
but it's not allowed during LRA process, so we defined few special move patterns
used for LRA, which will defer the expansion after LRA.

gcc/ChangeLog:

	PR target/109244
	* config/riscv/riscv-protos.h (emit_vlmax_vsetvl): Define as global.
	(emit_vlmax_op): Ditto.
	* config/riscv/riscv-v.cc (get_sew): New function.
	(emit_vlmax_vsetvl): Adapt function.
	(emit_pred_op): Ditto.
	(emit_vlmax_op): Ditto.
	(emit_nonvlmax_op): Ditto.
	(legitimize_move): Fix LRA ICE.
	(gen_no_side_effects_vsetvl_rtx): Adapt function.
	* config/riscv/vector.md (@mov<V_FRACT:mode><P:mode>_lra): New pattern.
	(@mov<VB:mode><P:mode>_lra): Ditto.
	(*mov<V_FRACT:mode><P:mode>_lra): Ditto.
	(*mov<VB:mode><P:mode>_lra): Ditto.

gcc/testsuite/ChangeLog:

	PR target/109244
	* g++.target/riscv/rvv/base/pr109244.C: New test.
	* gcc.target/riscv/rvv/base/binop_vv_constraint-4.c: Adapt testcase.
	* gcc.target/riscv/rvv/base/binop_vv_constraint-6.c: Ditto.
	* gcc.target/riscv/rvv/base/binop_vx_constraint-127.c: Ditto.
	* gcc.target/riscv/rvv/base/spill-1.c: Ditto.
	* gcc.target/riscv/rvv/base/spill-2.c: Ditto.
	* gcc.target/riscv/rvv/base/spill-3.c: Ditto.
	* gcc.target/riscv/rvv/base/spill-5.c: Ditto.
	* gcc.target/riscv/rvv/base/spill-7.c: Ditto.
	* g++.target/riscv/rvv/base/bug-18.C: New test.
	* gcc.target/riscv/rvv/base/merge_constraint-3.c: New test.
	* gcc.target/riscv/rvv/base/merge_constraint-4.c: New test.