sdt*exp: When the compiler doesn't recognize flag, mark test as UNTESTED.

sdt*exp: When the compiler doesn't recognize flag, mark test as UNTESTED.

Older gcc compilers don't recognize all the -std=[c|gnu]++0x flags we
throw at them. Instead of marking these compilations as FAIL, mark them
as UNTESTED now, so we only see real FAILures in the result (there are
still a couple left against -pedantic).