patch 8.1.2062: the mouse code is spread out

Problem:    The mouse code is spread out.
Solution:   Move all the mouse code to mouse.c. (Yegappan Lakshmanan,
            closes #4959)
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index dceb1a7..6ae5969 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -4221,9 +4221,7 @@
 		     * properly */
 		    save_State = State;
 		    State = CONFIRM;
-#ifdef FEAT_MOUSE
-		    setmouse();		/* disable mouse in xterm */
-#endif
+		    setmouse();		// disable mouse in xterm
 		    curwin->w_cursor.col = regmatch.startpos[0].col;
 		    if (curwin->w_p_crb)
 			do_check_cursorbind();
@@ -4397,9 +4395,7 @@
 			    scrolldown_clamp();
 		    }
 		    State = save_State;
-#ifdef FEAT_MOUSE
 		    setmouse();
-#endif
 		    if (vim_strchr(p_cpo, CPO_UNDO) != NULL)
 			--no_u_sync;