musl doesn't define W* macros.
---
--- a/src/ptyxis-application.c
+++ b/src/ptyxis-application.c
@@ -42,6 +42,10 @@
 #define PORTAL_OBJECT_PATH "/org/freedesktop/portal/desktop"
 #define PORTAL_SETTINGS_INTERFACE "org.freedesktop.portal.Settings"
 
+#ifndef W_EXITCODE
+#define W_EXITCODE(ret, sig)  ((ret) << 8 | (sig))
+#endif
+
 struct _PtyxisApplication
 {
   AdwApplication       parent_instance;