Fix rmul definition

rmul means "exit underline mode", so a full reset of all
the attributes is not the correct way of exiting from
underline mode, because it is going to modify also another
attributes not related.

st.info

@@ -161,7 +161,7 @@ st| simpleterm,
 	rmir=\E[4l,
 	rmkx=\E[?1l\E>,
 	rmso=\E[27m,
-	rmul=\E[m,
+	rmul=\E[24m,
 	rs1=\Ec,
 	rs2=\E[4l\E>\E[?1034l,
 	sc=\E7,