patch 8.0.0342: double free with EXITFREE and setting 'ttytype'

Problem:    Double free when compiled with EXITFREE and setting 'ttytype'.
Solution:   Avoid setting P_ALLOCED on 'ttytype'. (Dominique Pelle,
            closes #1461)
diff --git a/src/option.c b/src/option.c
index b5f3a9a..48a8048 100644
--- a/src/option.c
+++ b/src/option.c
@@ -3775,7 +3775,7 @@
 	if (options[i].indir == PV_NONE)
 	{
 	    /* global option: free value and default value. */
-	    if (options[i].flags & P_ALLOCED && options[i].var != NULL)
+	    if ((options[i].flags & P_ALLOCED) && options[i].var != NULL)
 		free_string_option(*(char_u **)options[i].var);
 	    if (options[i].flags & P_DEF_ALLOCED)
 		free_string_option(options[i].def_val[VI_DEFAULT]);
@@ -5929,8 +5929,14 @@
 	else if (set_termname(T_NAME) == FAIL)
 	    errmsg = (char_u *)N_("E522: Not found in termcap");
 	else
+	{
 	    /* Screen colors may have changed. */
 	    redraw_later_clear();
+
+	    /* Both 'term' and 'ttytype' point to T_NAME, only set the
+	     * P_ALLOCED flag on 'term'. */
+	    opt_idx = findoption((char_u *)"term");
+	}
     }
 
     /* 'backupcopy' */