r179385 - Disable following tests for Hexagon:

[Rafael Espíndola]

> 1) Driver/output-file-is-dir.c - Checks for object file which can't
> be created for Hexagon since assembler is unavailable.

I think I got a better fix in 17946.

> 2) PCH/cxx-typeid.cpp - 'typeinfo' include file is unavailable for Hexagon.
>

I could not figure out what this is testing :-(

Argyrios, could the include be replaced with just the declarations the
header needs?

Cheers,
Rafael