YYFAIL: warn about uses and remove from lalr1.java.

* NEWS (2.5): Document.
* data/lalr1.java (parser::YYStack::YYFAIL): Rename to YYERRLAB,
and make it private.  Update all uses.
* src/scan-code.l (SC_RULE_ACTION): Implement warning.
(cherry picked from commit 4395a9ff4f)

Conflicts:

	data/lalr1.java

src/scan-code.l

@@ -245,7 +245,20 @@ ref      -?[0-9]+|{id}|"["{id}"]"|"$"
   {splice}  STRING_GROW;
   [\n\r]    STRING_GROW; if (in_cpp) in_cpp = need_semicolon = false; 
   [ \t\f]   STRING_GROW;
-  .         STRING_GROW; need_semicolon = true;
+
+  /* YYFAIL is undocumented and was formally deprecated in Bison
+     2.4.2.  */
+  YYFAIL {
+    STRING_GROW; need_semicolon = true;
+    warn_at (*loc, _("use of YYFAIL, which is deprecated and will be"
+                     " removed"));
+  }
+
+  /* The sole purpose of this is to make sure identifiers that merely
+     contain YYFAIL don't produce the above warning.  */
+  [A-Za-z_][0-9A-Za-z_]* STRING_GROW; need_semicolon = true;
+
+  . STRING_GROW; need_semicolon = true;
 }
 
 <SC_SYMBOL_ACTION>