patch 8.1.1872: when Vim exits because of a signal, VimLeave is not triggered

Problem:    When Vim exits because of a signal, VimLeave is not triggered.
            (Daniel Hahler)
Solution:   Unblock autocommands when triggering VimLeave. (closes #4818)

src/main.c

@@ -1485,7 +1485,19 @@ getout(int exitval)
 #endif
 
     if (v_dying <= 1)
+    {
+	int	unblock = 0;
+
+	// deathtrap() blocks autocommands, but we do want to trigger VimLeave.
+	if (is_autocmd_blocked())
+	{
+	    unblock_autocmds();
+	    ++unblock;
+	}
 	apply_autocmds(EVENT_VIMLEAVE, NULL, NULL, FALSE, curbuf);
+	if (unblock)
+	    block_autocmds();
+    }
 
 #ifdef FEAT_PROFILE
     profile_dump();

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1872,
 /**/
     1871,
 /**/