patch 8.1.0070: missing part of the changes for prompt_setinterrupt()

Problem:    Missing part of the changes for prompt_setinterrupt().
Solution:   Add the missing changes.

src/structs.h

@@ -2360,6 +2360,8 @@ struct file_buffer
     char_u	*b_prompt_text;	     // set by prompt_setprompt()
     char_u	*b_prompt_callback;  // set by prompt_setcallback()
     partial_T	*b_prompt_partial;   // set by prompt_setcallback()
+    char_u	*b_prompt_interrupt;   // set by prompt_setinterrupt()
+    partial_T	*b_prompt_int_partial; // set by prompt_setinterrupt()
     int		b_prompt_insert;     // value for restart_edit when entering
 				     // a prompt buffer window.
 #endif

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    70,
 /**/
     69,
 /**/