middle-end/105965 - add missing v_c_e <{ el }> simplification

middle-end/105965 - add missing v_c_e <{ el }> simplification

When we got the simplification of bit-field-ref to view-convert
we lost the ability to detect FMAs since we cannot look through

  _1 = {_10};
  _11 = VIEW_CONVERT_EXPR<float>(_1);

the following amends the (view_convert CONSTRUCTOR) pattern
to handle this case.

2022-06-14  Richard Biener  <rguenther@suse.de>

	PR middle-end/105965
	* match.pd (view_convert CONSTRUCTOR): Handle single-element
	CTOR case.

	* gcc.target/i386/pr105965.c: New testcase.

(cherry picked from commit 90467f0ad649d0817f9e034596a0fb85605b55af)