Enable blinking in st.

config.def.h

@@ -20,6 +20,9 @@ static bool allowaltscreen = true;
 static unsigned int xfps = 60;
 static unsigned int actionfps = 30;
 
+/* blinking timeout (set to 0 to disable blinking) */
+static unsigned int blinktimeout = 800;
+
 /* TERM value */
 static char termname[] = "st-256color";