[lldb][ARM] Misc improvements to TestEmulations

* Look for files that end width arm/thumb.dat,
  meaning we don't try to run, for example, vim swap files.
* Print the name of the test that failed.

Reviewed By: clayborg

Differential Revision: https://reviews.llvm.org/D130467

GitOrigin-RevId: c4b6e5f9500fc3c44d587896eb402c8ede21eb10
1 file changed