gccrs: ast: Remove ExprStmtWithBlock / ExprStmtWithoutBlock distinction

gccrs: ast: Remove ExprStmtWithBlock / ExprStmtWithoutBlock distinction

This distinction isn't very helpful and makes correct parsing harder.

gcc/rust/ChangeLog:

	* ast/rust-ast-full-decls.h (class ExprStmtWithoutBlock): Remove.
	(class ExprStmtWithBlock): Remove.
	* ast/rust-stmt.h (class ExprStmtWithoutBlock): Remove.
	(class ExprStmtWithBlock): Remove.
	(class ExprStmt):
	Make non-abstract, add common functionality from removed base classes.
	* ast/rust-ast.h: Move to_stmt to base class.
	* ast/rust-ast.cc (ExprStmtWithBlock::as_string): Remove.
	* ast/rust-macro.h: Use new signature for to_stmt.
	(ExprStmt::as_string): New method.
	(ExprStmtWithoutBlock::as_string): Remove.
	(BlockExpr::strip_tail_expr): Update for removed classes.
	(ExprStmtWithoutBlock::accept_vis): Remove.
	(ExprStmtWithBlock::accept_vis): Remove.
	(ExprStmt::accept_vis): New method.
	* ast/rust-ast-dump.cc (Dump::visit): Update for removed classes.
	* ast/rust-ast-dump.h: Likewise.
	* ast/rust-ast-collector.h: Likewise.
	* ast/rust-ast-collector.cc (TokenStream::visit): Likewise.
	* ast/rust-ast-visitor.h: Likewise.
	* checks/errors/rust-feature-gate.h: Likewise.
	* expand/rust-expand-visitor.cc (ExpandVisitor::visit): Likewise.
	* expand/rust-expand-visitor.h: Likewise.
	* expand/rust-cfg-strip.cc (CfgStrip::visit): Likewise.
	* expand/rust-cfg-strip.h: Likewise.
	* hir/rust-ast-lower-base.cc (ASTLoweringBase::visit): Likewise.
	* hir/rust-ast-lower-base.h: Likewise.
	* hir/rust-ast-lower-stmt.cc (ASTLoweringStmt::visit): Likewise.
	* hir/rust-ast-lower-stmt.h: Likewise.
	* util/rust-attributes.cc (AttributeChecker::visit): Likewise.
	* util/rust-attributes.h: Likewise.
	* resolve/rust-ast-resolve-base.cc (ResolverBase::visit): Likewise.
	* resolve/rust-ast-resolve-base.h: Likewise.
	* resolve/rust-ast-resolve-stmt.h: Likewise.
	* resolve/rust-early-name-resolver.cc (EarlyNameResolver::visit):
	Likewise.
	* resolve/rust-early-name-resolver.h: Likewise.
	* parse/rust-parse-impl.h (Parser::parse_match_expr): Likewise.
	(Parser::parse_stmt_or_expr_without_block): Likewise.
	* parse/rust-parse.h: Likewise.

Signed-off-by: Matthew Jasper <mjjasper1@gmail.com>