Finish gimple_build API enhancement

Finish gimple_build API enhancement

This finishes the remaining parts of the gimple_build API enhancement,
converting the remaining workers to receive a gimple_stmt_iterator,
direction and update argument.  It also moves the code_helper
receiving functions from gimple-match.h to gimple-fold.h.

2022-05-16  Richard Biener  <rguenther@suse.de>

	* gimple-match.h (gimple_build): Move code_helper overloads ...
	* gimple-fold.h (gimple_build): ... here.
	(gimple_build): Transition to new worker API.  Provide
	overloads from sequence-based API.
	(gimple_convert): Likewise.
	(gimple_convert_to_ptrofftype): Likewise.
	(gimple_build_vector_from_val): Likewise.
	(gimple_build_vector): Likewise.
	(gimple_build_round_up): Likewise.
	* gimple-fold.cc (gimple_build_insert_seq): New helper.
	(gimple_build): Use it.  Transition combined_fn and code_helper
	API parts.
	(gimple_convert): Transition to new worker API.
	(gimple_convert_to_ptrofftype): Likewise.
	(gimple_build_vector_from_val): Likewise.
	(gimple_build_vector): Likewise.
	(gimple_build_round_up): Likewise.