RISC-V: Add more SLP tests

RISC-V: Add more SLP tests

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/partial/slp-10.c: New test.
	* gcc.target/riscv/rvv/autovec/partial/slp-11.c: New test.
	* gcc.target/riscv/rvv/autovec/partial/slp-13.c: New test.
	* gcc.target/riscv/rvv/autovec/partial/slp-14.c: New test.
	* gcc.target/riscv/rvv/autovec/partial/slp-15.c: New test.
	* gcc.target/riscv/rvv/autovec/partial/slp_run-10.c: New test.
	* gcc.target/riscv/rvv/autovec/partial/slp_run-11.c: New test.
	* gcc.target/riscv/rvv/autovec/partial/slp_run-13.c: New test.
	* gcc.target/riscv/rvv/autovec/partial/slp_run-14.c: New test.
	* gcc.target/riscv/rvv/autovec/partial/slp_run-15.c: New test.