river-options: free options of destroyed outputs

This is done when river's internal Output struct is destroyed, not when
the advertised wl_output global is removed. This means that options will
persist when an output is disabled and re-enabled.

 river/Option.zig         | 1 +
 river/OptionsManager.zig | 7 +++++++
 river/Output.zig         | 2 ++
 3 files changed, 10 insertions(+)

diff --git a/river/Option.zig b/river/Option.zig
index 1008d5f..a6366bc 100644
--- a/river/Option.zig
+++ b/river/Option.zig
@@ -67,6 +67,7 @@ pub fn destroy(self: *Self) void {
     var it = self.handles.safeIterator(.forward);
     while (it.next()) |handle| handle.destroy();
     if (self.value == .string) if (self.value.string) |s| util.gpa.free(mem.span(s));
+    self.link.remove();
     util.gpa.destroy(self);
 }
 
diff --git a/river/OptionsManager.zig b/river/OptionsManager.zig
index a3e2876..9d895dd 100644
--- a/river/OptionsManager.zig
+++ b/river/OptionsManager.zig
@@ -44,6 +44,13 @@ pub fn init(self: *Self, server: *Server) !void {
     server.wl_server.addDestroyListener(&self.server_destroy);
 }
 
+pub fn handleOutputDestroy(self: *Self, output: *Output) void {
+    var it = self.options.safeIterator(.forward);
+    while (it.next()) |option| {
+        if (option.output == output) option.destroy();
+    }
+}
+
 fn handleServerDestroy(listener: *wl.Listener(*wl.Server), wl_server: *wl.Server) void {
     const self = @fieldParentPtr(Self, "server_destroy", listener);
     self.global.destroy();
diff --git a/river/Output.zig b/river/Output.zig
index c8cd6c3..1b599ef 100644
--- a/river/Output.zig
+++ b/river/Output.zig
@@ -487,6 +487,8 @@ fn handleDestroy(listener: *wl.Listener(*wlr.Output), wlr_output: *wlr.Output) v
 
     log.debug(.server, "output '{}' destroyed", .{self.wlr_output.name});
 
+    root.server.options_manager.handleOutputDestroy(self);
+
     // Remove the destroyed output from root if it wasn't already removed
     root.removeOutput(self);