RISC-V: Support VLS floating-point extend/truncate
Regression passed.
Committed.
gcc/ChangeLog:
* config/riscv/vector-iterators.md: Extend VLS floating-point.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/rvv/autovec/widen/widen-10.c: Adapt test.
* gcc.target/riscv/rvv/autovec/widen/widen-11.c: Ditto.
* gcc.target/riscv/rvv/autovec/widen/widen-12.c: Ditto.
* gcc.target/riscv/rvv/autovec/widen/widen-complicate-7.c: Ditto.
* gcc.target/riscv/rvv/autovec/widen/widen-complicate-8.c: Ditto.
* gcc.target/riscv/rvv/autovec/widen/widen-complicate-9.c: Ditto.
* gcc.target/riscv/rvv/autovec/vls/ext-4.c: New test.
* gcc.target/riscv/rvv/autovec/vls/ext-5.c: New test.
* gcc.target/riscv/rvv/autovec/vls/trunc-4.c: New test.
* gcc.target/riscv/rvv/autovec/vls/trunc-5.c: New test.