gdbstub: call socket_set_fast_reuse instead of setting SO_REUSEADDR

SO_REUSEADDR should be avoided on Windows but is desired on other operating
systems. So instead of setting it we call socket_set_fast_reuse that will result
in the appropriate behaviour on all operating systems.
Signed-off-by: NSebastian Ottlik <ottlik@fzi.de>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NStefan Weil <sw@weilnetz.de>

gdbstub.c

@@ -1553,7 +1553,7 @@ static void gdb_accept(void)
 static int gdbserver_open(int port)
 {
     struct sockaddr_in sockaddr;
-    int fd, val, ret;
+    int fd, ret;
 
     fd = socket(PF_INET, SOCK_STREAM, 0);
     if (fd < 0) {
@@ -1564,9 +1564,7 @@ static int gdbserver_open(int port)
     fcntl(fd, F_SETFD, FD_CLOEXEC);
 #endif
 
-    /* allow fast reuse */
-    val = 1;
-    qemu_setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
+    socket_set_fast_reuse(fd);
 
     sockaddr.sin_family = AF_INET;
     sockaddr.sin_port = htons(port);