https://bugs.gentoo.org/969495
https://crbug.com/456218403
--- a/src/3rdparty/chromium/sandbox/linux/system_headers/linux_seccomp.h
+++ b/src/3rdparty/chromium/sandbox/linux/system_headers/linux_seccomp.h
@@ -7,4 +7,5 @@
 
 #include <stdint.h>
+#include <signal.h>
 #include <sys/ioctl.h>