RISC-V:Add float16 tuple type support

RISC-V:Add float16 tuple type support

This patch adds support for the float16 tuple type.

gcc/ChangeLog:

	* config/riscv/genrvv-type-indexer.cc (valid_type): Enable FP16 tuple.
	* config/riscv/riscv-modes.def (RVV_TUPLE_MODES): New macro.
	(ADJUST_ALIGNMENT): Ditto.
	(RVV_TUPLE_PARTIAL_MODES): Ditto.
	(ADJUST_NUNITS): Ditto.
	* config/riscv/riscv-vector-builtins-types.def (vfloat16mf4x2_t):
	New types.
	(vfloat16mf4x3_t): Ditto.
	(vfloat16mf4x4_t): Ditto.
	(vfloat16mf4x5_t): Ditto.
	(vfloat16mf4x6_t): Ditto.
	(vfloat16mf4x7_t): Ditto.
	(vfloat16mf4x8_t): Ditto.
	(vfloat16mf2x2_t): Ditto.
	(vfloat16mf2x3_t): Ditto.
	(vfloat16mf2x4_t): Ditto.
	(vfloat16mf2x5_t): Ditto.
	(vfloat16mf2x6_t): Ditto.
	(vfloat16mf2x7_t): Ditto.
	(vfloat16mf2x8_t): Ditto.
	(vfloat16m1x2_t): Ditto.
	(vfloat16m1x3_t): Ditto.
	(vfloat16m1x4_t): Ditto.
	(vfloat16m1x5_t): Ditto.
	(vfloat16m1x6_t): Ditto.
	(vfloat16m1x7_t): Ditto.
	(vfloat16m1x8_t): Ditto.
	(vfloat16m2x2_t): Ditto.
	(vfloat16m2x3_t): Ditto.
	(vfloat16m2x4_t): Ditto.
	(vfloat16m4x2_t): Ditto.
	* config/riscv/riscv-vector-builtins.def (vfloat16mf4x2_t): New macro.
	(vfloat16mf4x3_t): Ditto.
	(vfloat16mf4x4_t): Ditto.
	(vfloat16mf4x5_t): Ditto.
	(vfloat16mf4x6_t): Ditto.
	(vfloat16mf4x7_t): Ditto.
	(vfloat16mf4x8_t): Ditto.
	(vfloat16mf2x2_t): Ditto.
	(vfloat16mf2x3_t): Ditto.
	(vfloat16mf2x4_t): Ditto.
	(vfloat16mf2x5_t): Ditto.
	(vfloat16mf2x6_t): Ditto.
	(vfloat16mf2x7_t): Ditto.
	(vfloat16mf2x8_t): Ditto.
	(vfloat16m1x2_t): Ditto.
	(vfloat16m1x3_t): Ditto.
	(vfloat16m1x4_t): Ditto.
	(vfloat16m1x5_t): Ditto.
	(vfloat16m1x6_t): Ditto.
	(vfloat16m1x7_t): Ditto.
	(vfloat16m1x8_t): Ditto.
	(vfloat16m2x2_t): Ditto.
	(vfloat16m2x3_t): Ditto.
	(vfloat16m2x4_t): Ditto.
	(vfloat16m4x2_t): Ditto.
	* config/riscv/riscv-vector-switch.def (TUPLE_ENTRY): New.
	* config/riscv/riscv.md: New.
	* config/riscv/vector-iterators.md: New.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/base/tuple-28.c: New test.
	* gcc.target/riscv/rvv/base/tuple-29.c: New test.
	* gcc.target/riscv/rvv/base/tuple-30.c: New test.
	* gcc.target/riscv/rvv/base/tuple-31.c: New test.
	* gcc.target/riscv/rvv/base/tuple-32.c: New test.