[v3] cleanup testsuite for newlib targets

[Benjamin Kosnik]

> Yes, -std=gnu++0x works, but why should I now need this to include fenv.h?

fenv.h is specified as a compatibility header for cfenv. I recently 
added this to the list of files that exists with the default header 
strategy, but neglected to add in the scopes to global for types and 
functions, whoops.

See TR1 8.7.

Doing this won't solve all your errors, however.

-benjamin