This patch updates the lld lit test config to use the internal shell by
default. This has some performance advantages (~10-15%) and also
produces nicer failure output. It also updates the two LLDB tests to not
require shell (so that they run under the internal shell), after first
verifying that they run and pass using the internal shell; and it fixes
one test that was not passing under the internal shell.
%T has been deprecated for about seven years, mostly because it is not
unique to each test which can lead to races. This patch updates the few
remaining tests in lldb that use %T to not use it (either directly using
files or creating their own temp dir). The eventual goal is to remove
support for %T from llvm-lit given few tests use it and it still has
racey behavior.
This patch errors on the side of creating new temp dirs even when not
strictly necessary to avoid needing to update filenames inside filecheck
matchers.
When the debug info refers to a dwo with relative `DW_AT_comp_dir` and
`DW_AT_dwo_name`, we only print the `DW_AT_comp_dir` in our error
message if we can't find it. This often isn't very helpful, especially
when the `DW_AT_comp_dir` is ".":
```
(lldb) fr v
error: unable to locate .dwo debug file "." for skeleton DIE 0x000000000000003c
```
I'm updating the error message to include both `DW_AT_comp_dir` (if it
exists) and `DW_AT_dwo_name` when the `DW_AT_dwo_name` is relative. The
behavior when `DW_AT_dwo_name` is absolute should be the same.
