LoongArch: Add tests for ASX vector comparison and selection instruction.
gcc/testsuite/ChangeLog:
* gcc.target/loongarch/vector/lasx/lasx-xvseq.c: New test.
* gcc.target/loongarch/vector/lasx/lasx-xvseqi.c: New test.
* gcc.target/loongarch/vector/lasx/lasx-xvsle-1.c: New test.
* gcc.target/loongarch/vector/lasx/lasx-xvsle-2.c: New test.
* gcc.target/loongarch/vector/lasx/lasx-xvslei-1.c: New test.
* gcc.target/loongarch/vector/lasx/lasx-xvslei-2.c: New test.
* gcc.target/loongarch/vector/lasx/lasx-xvslt-1.c: New test.
* gcc.target/loongarch/vector/lasx/lasx-xvslt-2.c: New test.
* gcc.target/loongarch/vector/lasx/lasx-xvslti-1.c: New test.
* gcc.target/loongarch/vector/lasx/lasx-xvslti-2.c: New test.