Fix crash on startup when script debugging is enabled due to shared signals between mono and the GC (case 973794)

Author: mderoy

mono/utils/mono-threads-posix-signals.c

@@ -84,7 +84,7 @@ static int
 suspend_signal_get (void)
 {
 #if defined(HOST_ANDROID)
-	return SIGPWR;
+	return SIGUSR1;
 #elif defined (SIGRTMIN)
 	static int suspend_signum = -1;
 	if (suspend_signum == -1)
@@ -103,7 +103,7 @@ static int
 restart_signal_get (void)
 {
 #if defined(HOST_ANDROID)
-	return SIGXCPU;
+	return SIGUSR2;
 #elif defined (SIGRTMIN)
 	static int restart_signum = -1;
 	if (restart_signum == -1)