https://git.alpinelinux.org/aports/commit/testing/mame/fix-musl.patch?id=0ca943c72056e9ce2cc8f26d9ca7797cf5d04575

--- a/src/osd/modules/sound/pulse_sound.cpp
+++ b/src/osd/modules/sound/pulse_sound.cpp
@@ -19,6 +19,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <poll.h>
+#include <signal.h>
 
 #include <thread>
 #include <pulse/pulseaudio.h>