states/hl/cpp.st: Update C++ keyword list.

states/hl/cpp.st: Update C++ keyword list.

Based on keyword list at http://en.cppreference.com/w/cpp/keyword.

(As per:
http://en.cppreference.com/w/Cppreference:FAQ#What_can_I_do_with_the_material_on_this_site.3F
that page is licensed under the GFDL, unversioned, with no invariant
sections, front-cover texts, or back-cover texts.)

Savannah bug #40740.

Signed-off-by: James Cloos <cloos@jhcloos.com>