patch 8.0.0746: when :term fails the job is not properly cleaned up

Problem:    When :term fails the job is not properly cleaned up.
Solution:   Free the terminal. Handle a job that failed to start. (closes
            #1858)

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    746,
 /**/
     745,
 /**/