also support $<foo>$ in the %initial-action

scan-code.l is already passing argument to b4_dollar_dollar for the
initial acton, but its definition (of b4_dollar_dollar) does not use
this argument.

Generalize this definition, and use it for the %initial-action too.

* data/c.m4 (b4_dollar_dollar_, b4_dollar_pushdef, b4_dollar_popdef):
Instead of expecting a pointer, require a value, and use ".".
Since they are now generic enough, move to...
* data/c-like.m4: this new file.
* data/c.m4, data/java.m4: Load it.
* data/glr.c, data/lalr1.cc, data/lalr1.java, data/yacc.c: Use
b4_dollar_pushdef for the %initial-action.
* tests/actions.at: Check that.
* data/Makefile.am: Adjust.
* NEWS, doc/bison.texi: Document.

data/c-like.m4

@@ -0,0 +1,44 @@
+                                                            -*- Autoconf -*-
+
+# Common code for C-like languages (C, C++, Java, etc.)
+
+# Copyright (C) 2012 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# b4_dollar_dollar_(VALUE, FIELD, DEFAULT-FIELD)
+# ----------------------------------------------
+# If FIELD (or DEFAULT-FIELD) is non-null, return "VALUE.FIELD",
+# otherwise just VALUE.  Be sure to pass "(VALUE)" is VALUE is a
+# pointer.
+m4_define([b4_dollar_dollar_],
+[m4_if([$2], [[]],
+       [m4_ifval([$3], [($1.$3)],
+                 [$1])],
+       [($1.$2)])])
+
+# b4_dollar_pushdef(VALUE-POINTER, DEFAULT-FIELD, LOCATION)
+# b4_dollar_popdef
+# ---------------------------------------------------------
+# Define b4_dollar_dollar for VALUE and DEFAULT-FIELD,
+# and b4_at_dollar for LOCATION.
+m4_define([b4_dollar_pushdef],
+[m4_pushdef([b4_dollar_dollar],
+            [b4_dollar_dollar_([$1], m4_dquote($][1), [$2])])dnl
+m4_pushdef([b4_at_dollar], [$3])dnl
+])
+m4_define([b4_dollar_popdef],
+[m4_popdef([b4_at_dollar])dnl
+m4_popdef([b4_dollar_dollar])dnl
+])