RISC-V: Add optimized dump check of VLS reduc tests

RISC-V: Add optimized dump check of VLS reduc tests

Add more dump check to robostify the tests.

Committed.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/vls/reduc-1.c: Add dump check.
	* gcc.target/riscv/rvv/autovec/vls/reduc-10.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-11.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-12.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-13.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-14.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-15.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-16.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-17.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-18.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-19.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-2.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-20.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-21.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-3.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-4.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-5.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-6.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-7.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-8.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls/reduc-9.c: Ditto.