More header fixes

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/common.h

@@ -60,6 +60,7 @@
 #include "utils.h"
 #include "list.h"
 #include "render.h"
+#include "win_defs.h"
 #include "x.h"
 
 // === Constants ===0

src/compton.modulemap

@@ -41,8 +41,12 @@ module opengl {
 module diagnostic {
   header "diagnostic.h"
 }
+module win_defs {
+  header "win_defs.h"
+}
 module win {
   header "win.h"
+  export win_defs
 }
 module log {
   header "log.h"