[NFC][DWARF] Add triple to new TAG test file

The file is requiring x86, but using llc without triple.

This will cause problem on non-x86 platforms, as the default triple will
not be x86.

eg: On PowerPC le, it will emit warnings as:

'x86-64' is not a recognized processor for this target (ignoring
processor)
'+cx8' is not a recognized feature for this target (ignoring feature)
'+fxsr' is not a recognized feature for this target (ignoring feature)
'+mmx' is not a recognized feature for this target (ignoring feature)
'+sse' is not a recognized feature for this target (ignoring feature)
..

On some other platform, it may even crash -- if some of the feature are
with same name (eg: soft-float).

Add the triple as this was the intention test target.