Internal-fn: Introduce new IFN MASK_LEN_STRIDED_LOAD{STORE}

Internal-fn: Introduce new IFN MASK_LEN_STRIDED_LOAD{STORE}

This patch would like to introduce new IFN for strided load and store.

LOAD:  v = MASK_LEN_STRIDED_LOAD (ptr, stride, mask, len, bias)
STORE: MASK_LEN_STRIED_STORE (ptr, stride, v, mask, len, bias)

The IFN target below code example similar as below

void foo (int * a, int * b, int stride, int n)
{
  for (int i = 0; i < n; i++)
    a[i * stride] = b[i * stride];
}

The below test suites are passed for this patch.
* The rv64gcv fully regression test.
* The x86 bootstrap test.
* The x86 fully regression test.

gcc/ChangeLog:

	* internal-fn.cc (strided_load_direct): Add new define direct
	for strided load.
	(strided_store_direct): Ditto but for store.
	(expand_strided_load_optab_fn): Add new func to expand the IFN
	MASK_LEN_STRIDED_LOAD in middle-end.
	(expand_strided_store_optab_fn): Ditto but for store.
	(direct_strided_load_optab_supported_p): Add define for stride
	load optab supported.
	(direct_strided_store_optab_supported_p): Ditto but for store.
	(internal_fn_len_index): Add strided load/store len index.
	(internal_fn_mask_index): Ditto but for mask.
	(internal_fn_stored_value_index): Add strided store value index.
	* internal-fn.def (MASK_LEN_STRIDED_LOAD): Add new IFN for
	strided load.
	(MASK_LEN_STRIDED_STORE): Ditto but for store.
	* optabs.def (mask_len_strided_load_optab): Add strided load optab.
	(mask_len_strided_store_optab): Add strided store optab.

Signed-off-by: Pan Li <pan2.li@intel.com>
Co-Authored-By: Juzhe-Zhong <juzhe.zhong@rivai.ai>