Add the new specifiers and qualifiers for C11.
Change the constant expression rule wrt templates.

There is ambiguity in constant expressions about whether "<" is
an operator or a delimiter.  Previously the rule treated it as
an operator, but this patch makes the rule treat it as a delimiter.
Which is better?  Both are half-wrong, neither occur in VTK yet.
Use the bison GLR parser algorithm to resolve ambiguities.

This applies a hammer to the constant expression ambiguity problem
by having a rule that allows "<" to be either a less-than operator
or a template argument bracket.  The glr-parser tries both, and goes
with whichever choice results in a parseable input.
Check for EOF in addition to null as end of file marker.