XFAIL Headers/cxx11.cpp for Hexagon

[Jyotsna Verma]

>I would still like an explanation of the nature of the failure. Which
header or
>#include is problematic? Also, this isn't really a C++11 test, it's a test
for our
>built-in headers, and even if it were, I don't see why it'd be reasonable
to
>XFAIL C++11 tests for Hexagon.

We do define __STDC_HOSTED__ for Hexagon which probably shouldn't be.
The test includes stdint.h file from lib/Headers which in turn includes
system stdint.h if __STDC_HOSTED__ macro is defined. In addition, it also
requires some other system headers such as features.h, bits/predefs.h and
gnu/stubs-32.h. There is no way for us to make these header files available
in the build area.

Thanks,
Jyotsna