Use a static hierarchy for symbols in the C++ parser.

* data/lalr1.cc (symbol_base_type, symbol_type)
	(stack_symbol_type): Make it a static hierarchy.
	Adjust dependencies.

examples/variant.yy

@@ -1,7 +1,7 @@
 /* Test file for C++ parsers using variants.
    Based on an example by Michiel De Wilde <mdewilde.agilent@gmail.com>. */
 %debug
-%skeleton "lalr1-fusion.cc"
+%skeleton "lalr1.cc"
 %defines
 %define variant