RISC-V: Add vsaddu.vv C++ API tests.

RISC-V: Add vsaddu.vv C++ API tests.

gcc/testsuite/ChangeLog:

	* g++.target/riscv/rvv/base/vsaddu_vv-1.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv-2.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv-3.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv_mu-1.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv_mu-2.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv_mu-3.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv_tu-1.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv_tu-2.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv_tu-3.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv_tum-1.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv_tum-2.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv_tum-3.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv_tumu-1.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv_tumu-2.C: New test.
	* g++.target/riscv/rvv/base/vsaddu_vv_tumu-3.C: New test.