Add support for parsing C++11 final classes

Such as:

  class X final {};

This no longer gives a syntax error.
This change has introduced one more shift-reduce conflict in the parser.
with a conflict with a C style variable declaration with name final:

  class X final;

resulting in a syntax error (for C++ not C). This is an an unusual style
for C++ code and more typical declarations do work:

  X final;

Closes #672

Examples/test-suite/common.mk

@@ -592,6 +592,7 @@ CPP11_TEST_CASES += \
 	cpp11_director_enums \
 	cpp11_directors \
 	cpp11_explicit_conversion_operators \
+	cpp11_final_class \
 	cpp11_final_directors \
 	cpp11_final_override \
 	cpp11_function_objects \
@@ -755,6 +756,7 @@ C_TEST_CASES += \
 	enum_macro \
 	enum_missing \
 	extern_declaration \
+	final_c \
 	funcptr \
 	function_typedef \
 	global_functions \