[Bug c/63326] whether a #pragma is a statement depends on the type of pragma

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63326

--- Comment #18 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Chen Gang from comment #17)
> I guess the diff below should be OK, I shall give a make check test.

I would rather have the C front-end behavior for C++ rather than the opposite
way around.  Because _Pragma are considered statements.