RISC-V: Support FP round to i/l/ll diff size autovec

RISC-V: Support FP round to i/l/ll diff size autovec

This patch would like to support the FP below API auto vectorization
with different type size

+----------+-----------+----------+
| API      | RV64      | RV32     |
+----------+-----------+----------+
| iround   | DF => SI  | DF => SI |
| iroundf  | -         | -        |
| lround   | -         | DF => SI |
| lroundf  | SF => DI  | -        |
| llround  | -         | -        |
| llroundf | SF => DI  | SF => DI |
+----------+-----------+----------+

Given below code:
void
test_lroundf (long *out, float *in, unsigned count)
{
  for (unsigned i = 0; i < count; i++)
    out[i] = __builtin_lroundf (in[i]);
}

Before this patch:
.L3:
  flw      fa5,0(a1)
  addi     a1,a1,4
  addi     a0,a0,8
  fcvt.l.s a5,fa5,rmm
  sd       a5,-8(a0)
  bne      a4,a1,.L3

After this patch:
  fsrmi        4  // RMM rounding mode
  vsetivli     zero,16,e32,m4,ta,ma
.L4:
  vle32.v      v4,0(a5)
  addi         a5,a5,64
  vfwcvt.x.f.v v8,v4
  vse64.v      v8,0(a4)
  addi         a4,a4,128
  bne          a3,a5,.L4
  andi         a5,a2,15
  andi         a4,a2,-16
  beq          a5,zero,.L16

Unfortunately, the HF mode is not include due to it requires
additional middle-end support from internal-fun.def.

gcc/ChangeLog:

	* config/riscv/autovec.md: Remove the size check of lround.
	* config/riscv/riscv-v.cc (expand_vec_lround): Leverage
	emit_vec_rounding_to_integer for round.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/unop/math-iround-1.c: New test.
	* gcc.target/riscv/rvv/autovec/unop/math-iround-run-1.c: New test.
	* gcc.target/riscv/rvv/autovec/unop/math-llroundf-0.c: New test.
	* gcc.target/riscv/rvv/autovec/unop/math-llroundf-run-0.c: New test.
	* gcc.target/riscv/rvv/autovec/unop/math-lround-rv32-0.c: New test.
	* gcc.target/riscv/rvv/autovec/unop/math-lround-rv32-run-0.c: New test.
	* gcc.target/riscv/rvv/autovec/unop/math-lroundf-rv64-0.c: New test.
	* gcc.target/riscv/rvv/autovec/unop/math-lroundf-rv64-run-0.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/math-iround-1.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/math-llroundf-0.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/math-lround-rv32-0.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/math-lroundf-rv64-0.c: New test.

Signed-off-by: Pan Li <pan2.li@intel.com>