fold-const: Return corresponding integral type for OFFSET_TYPE in range_check_type...

fold-const: Return corresponding integral type for OFFSET_TYPE in range_check_type [PR101162]

Andrew's recent r12-1608-g2f1686ff70b25fceb04ca2ffc0a450fb682913ef change
to fail verification on various unary and binary operations with OFFSET_TYPE
revealed that e.g. switchconv happily performs multiplications and additions
in OFFSET_TYPE.

2021-06-22  Jakub Jelinek  <jakub@redhat.com>
	    Andrew Pinski  <apinski@marvell.com>

	PR tree-optimization/101162
	* fold-const.c (range_check_type): Handle OFFSET_TYPE like pointer
	types.

	* g++.dg/opt/pr101162.C: New test.