gccrs: Remove unused Context parameter for some backend methods

gccrs: Remove unused Context parameter for some backend methods

gcc/rust/ChangeLog:

	* backend/rust-compile-base.cc
	(HIRCompileBase::compile_function_body):
	Adjust unit_expression calls.
	(HIRCompileBase::unit_expression):
	Remove unused Context parameter.
	* backend/rust-compile-base.h
	(HIRCompileBase::unit_expression): Likewise.
	* backend/rust-compile-block.cc
	(CompileBlock::visit): Adjust unit_expression calls.
	* backend/rust-compile-expr.cc
	(CompileExpr::visit): Likewise.
	* backend/rust-compile-pattern.cc
	(CompilePatternLet::visit): Likewise.
	* backend/rust-compile-resolve-path.cc
	(ResolvePathRef::attempt_constructor_expression_lookup):
	Likewise.
	* backend/rust-compile-type.cc
	(TyTyResolveCompile::get_implicit_enumeral_node_type):
	Remove unused Context parameter.
	(TyTyResolveCompile::get_unit_type):
	Likewise.
	(TyTyResolveCompile::visit):
	Adjust get_implicit_enumeral_node_type and get_unit_type calls.
	* backend/rust-compile-type.h
	(TyTyResolveCompile::get_implicit_enumeral_node_type):
	Remove unused Context parameter.
	(TyTyResolveCompile::get_unit_type):
	Likewise.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>