Updated version of 0006-linux-user-signal.c-define-__SIGRTMIN-MAX-for-non-GN.patch for qemu-3.0.0
from alpine, original author Natanael Copa.
--- linux-user/signal.c	2018-09-04 10:23:03.244301111 +0200
+++ linux-user/signal.c	2018-09-04 10:29:52.333828797 +0200
@@ -26,6 +26,13 @@
 #include "trace.h"
 #include "signal-common.h"
 
+#ifndef __SIGRTMIN
+#define __SIGRTMIN 32
+#endif
+#ifndef __SIGRTMAX
+#define __SIGRTMAX (NSIG-1)
+#endif
+
 struct target_sigaltstack target_sigaltstack_used = {
     .ss_sp = 0,
     .ss_size = 0,