gccrs: Add missing location info to coercions

gccrs: Add missing location info to coercions

gcc/rust/ChangeLog:

	* typecheck/rust-hir-type-check-base.cc (TypeCheckBase::TypeCheckBase):
	Remove constructor.
	(TypeCheckBase::coercion_site): Add `Location` argument to function.
	* typecheck/rust-hir-type-check-base.h: Use `TypeCheckBase::coercion_site`
	function with location argument.
	* typecheck/rust-hir-type-check-enumitem.cc (TypeCheckEnumItem::visit): Likewise.
	* typecheck/rust-hir-type-check-expr.cc (TypeCheckExpr::visit): Likewise.
	* typecheck/rust-hir-type-check-expr.h (class TypeCheckExpr): Likewise.
	* typecheck/rust-hir-type-check-stmt.cc (TypeCheckStmt::visit): Likewise.
	* typecheck/rust-hir-type-check-struct.cc (TypeCheckStructExpr::visit): Likewise.
	* typecheck/rust-hir-type-check-toplevel.cc (TypeCheckTopLevel::visit): Likewise.
	* typecheck/rust-tyty-call.cc (TypeCheckCallExpr::visit): Likewise.
	(TypeCheckMethodCallExpr::visit): Likewise.
	* typecheck/rust-tyty.h: Add missing locus field.
	* typecheck/rust-tyty.cc (StructFieldType::clone): Use locus field.
	(StructFieldType::monomorphized_clone): Likewise.