[dmd-internals] Tests broken on all platforms

[David Nadlinger]

The auto tester is currently red on all the platforms because of an 
accepts-invalid regression the fix for 7793 introduced.

I put together a "minimal" patch which should be safe to apply in any 
case:
https://github.com/D-Programming-Language/dmd/pull/1024

As mentioned in the commit message, the code for 
StaticIfDeclaration::include is still somewhat clumsy, as the same check 
is essentially made twice.

David