PR target/106481: Handle CONST_WIDE_INT in REG_EQUAL during STV on x86_64.

PR target/106481: Handle CONST_WIDE_INT in REG_EQUAL during STV on x86_64.

This patch resolves PR target/106481, and is an oversight in my recent
battles with REG_EQUAL notes during TImode STV (see PR target/106278
https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598416.html).

The patch above's/current behaviour is that we check that the mode of
the REG_EQUAL note is TImode before using PUT_MODE to set it to V1TImode.
However, the new test case reveals that this doesn't consider REG_EQUAL
notes that are CONST_INT or CONST_WIDE_INT, i.e. that are VOIDmode,
and so STV produces:

(insn 85 84 86 2 (set (reg:V1TI 113)
        (reg:V1TI 84)) "pr106481.c":13:3 1766 {movv1ti_internal}
     (expr_list:REG_EQUAL (const_wide_int 0x0ffffffff00000004)
        (nil)))

which causes problems as the const_wide_int isn't a valid immediate
constant for V1TImode.  With this patch, we now generate the correct:

(insn 85 84 86 2 (set (reg:V1TI 113)
        (reg:V1TI 84)) "pr106481.c":13:3 1766 {movv1ti_internal}
     (expr_list:REG_EQUAL (const_vector:V1TI [
                (const_wide_int 0x0ffffffff00000004)
            ])
        (nil)))

2022-08-01  Roger Sayle  <roger@nextmovesoftware.com>
	    Uroš Bizjak  <ubizjak@gmail.com>

gcc/ChangeLog
	PR target/106481
	* config/i386/i386-features.cc (timode_scalar_chain::convert_insn):
	Convert a CONST_SCALAR_INT_P in a REG_EQUAL note into a V1TImode
	CONST_VECTOR.

gcc/testsuite/ChangeLog
	PR target/106481
	* gcc.target/i386/pr106481.c: New test case.