libstdc++ testsuite fixes, 2

[Benjamin Kosnik]

this is fine.

> Now, in this particular case, when it says deprecated, it means 'this
> feature _will_ be removed no later than 3.2, and in 3.1 if I can get
> away with it.'  Hence I think the test suite should be changed not to
> use multi-line string constants.  The appended patch accomplishes
> this.  Note that the deprecation warning is not what is being tested
> in any of these test cases (that's taken care of over in the C
> compiler's test suite).

this is a better way, indeed.

please check this in to both branch and head.

-benjamin