LoongArch: Add tests for SX vector vbitclr/vbitclri/vbitrev/vbitrevi/ vbitsel/vbitseli/vbitset/vbitseti/vclo/vclz/vpcnt instructions.
gcc/testsuite/ChangeLog:
* gcc.target/loongarch/vector/lsx/lsx-vbitclr.c: New test.
* gcc.target/loongarch/vector/lsx/lsx-vbitclri.c: New test.
* gcc.target/loongarch/vector/lsx/lsx-vbitrev.c: New test.
* gcc.target/loongarch/vector/lsx/lsx-vbitrevi.c: New test.
* gcc.target/loongarch/vector/lsx/lsx-vbitsel.c: New test.
* gcc.target/loongarch/vector/lsx/lsx-vbitseli.c: New test.
* gcc.target/loongarch/vector/lsx/lsx-vbitset.c: New test.
* gcc.target/loongarch/vector/lsx/lsx-vbitseti.c: New test.
* gcc.target/loongarch/vector/lsx/lsx-vclo.c: New test.
* gcc.target/loongarch/vector/lsx/lsx-vclz.c: New test.
* gcc.target/loongarch/vector/lsx/lsx-vpcnt.c: New test.