Reported by Rob Conde.
http://lists.gnu.org/archive/html/bug-bison/2013-03/msg00003.html
* data/stack.hh (operator=, stack(const stack&)): Make this class
uncopyable, i.e., "undefine" these operators: make them private and
don't implement them.
(clear): New.
* data/lalr1.cc: Use it instead of an assignment.
(parser): Make this class uncopyable.
Work on some other areas of Bison revealed that some macros expanded
to be expanded only once were actually expanded several times. This
was due to the fact that changecom was not properly restored each
time, and macro names appearing in comments were then expanded.
Introduce begin/end macros which are easier to match that
changecom()/changecom(#).
* data/bison.m4 (b4_output_begin, b4_output_end): New.
* data/glr.c, data/glr.cc, data/lalr1.cc, data/lalr1.java,
* data/location.cc, data/stack.hh, data/yacc.c:
Use them.
