RISC-V: Support VLS modes VEC_EXTRACT auto-vectorization

RISC-V: Support VLS modes VEC_EXTRACT auto-vectorization

This patch support VLS modes VEC_EXTRACT to fix PR111391:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111391

I need VLS modes VEC_EXTRACT to fix this issue.

I have run the whole gcc testsuite, notice this patch increase these 4 FAILs:
FAIL: c-c++-common/vector-subscript-4.c  -std=gnu++14  scan-tree-dump-not optimized "vector"
FAIL: c-c++-common/vector-subscript-4.c  -std=gnu++17  scan-tree-dump-not optimized "vector"
FAIL: c-c++-common/vector-subscript-4.c  -std=gnu++20  scan-tree-dump-not optimized "vector"
FAIL: c-c++-common/vector-subscript-4.c  -std=gnu++98  scan-tree-dump-not optimized "vector"

After analysis and comparing with LLVM:
https://godbolt.org/z/ozhfKhj5Y

with this patch, GCC generate similar codegen like LLVM (Previously it can not be vectorized).

This patch is the prerequisite patch to fix an ICE.

So let's ignore those increased 4 dump IR FAILs since ICE is un-acceptable wheras dump FAILs are acceptable (But we should remember and eventually fix dump IR FAILs too).

gcc/ChangeLog:

	* config/riscv/autovec.md (vec_extract<mode><vel>): Add VLS modes.
	(@vec_extract<mode><vel>): Ditto.
	* config/riscv/vector.md: Ditto

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/vls/def.h: Add more def.
	* gcc.target/riscv/rvv/autovec/vls/extract-1.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/extract-2.c: New test.