Move damage tracking to separate file

include/damage.h

@@ -0,0 +1,27 @@
+#ifndef GSR_DAMAGE_H
+#define GSR_DAMAGE_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+typedef struct _XDisplay Display;
+typedef union _XEvent XEvent;
+
+typedef struct {
+    Display *display;
+    int damage_event;
+    int damage_error;
+    uint64_t damage;
+    bool damaged;
+} gsr_damage;
+
+bool gsr_damage_init(gsr_damage *self, Display *display);
+void gsr_damage_deinit(gsr_damage *self);
+
+bool gsr_damage_set_target_window(gsr_damage *self, uint64_t window);
+void gsr_damage_update(gsr_damage *self, XEvent *xev);
+/* Also returns true if damage tracking is not available */
+bool gsr_damage_is_damaged(gsr_damage *self);
+void gsr_damage_clear(gsr_damage *self);
+
+#endif /* GSR_DAMAGE_H */