This fix is based on a problem with cxx_compiler and cxx_linker macros
on Windows.
There was an issue with compiler detection in paths containing "icc". In
such case, Makefile.rules thought it was provided with icc compiler.

To solve that, utilities detection has been rewritten in Python.
The last element of compiler's path is separated, taking into account
the platform path delimiter, and compiler type is extracted, with regard
of possible cross-toolchain prefix.

---------

Co-authored-by: Pavel Labath <pavel@labath.sk>

The only change is a fix for the "register" iterator test to not rely on
particular register names.

I mistook where the artificial "pc" register is generated. It isn't
added to the register list or the register sets (except on arm where
that's the name of the actual register), so I can't use it in this test.
I instead just assert that the "register" generator produces the same
list as flattening the register sets from "registers".

This reverts commit 9f14914753599f3879e4c273191959e2f1b3632c.

Reverts llvm/llvm-project#88047. TestFrames.py is failing on x86_64
GreenDragon:
https://green.lab.llvm.org/job/llvm.org/view/LLDB/job/lldb-cmake/983/

The code returned lldb.SBValue() when you passed in an unrecognized
register name. But referring to "lldb" is apparently not legal within
the module.

I changed this to just return SBValue(), but then this construct:

(lldb) script
>>> for reg_set in lldb.target.process.thread[0].frames[0].register
...    print(reg)

Runs forever printing "No Value". The __getitem__(key) gets called with
a monotonically increasing by 1 series of integers. I don't know why
Python decided the class we defined should have a generator that returns
positive integers in order, but we can add a more useful one here by
returning an iterator over the flattened list of registers.

Note, the not very aptly named "SBFrame.registers" is an iterator over
register sets, not registers, so the two are not redundant.

This uses [teyit](https://pypi.org/project/teyit/) to modernize asserts,
as recommended by the [unittest release
notes](https://docs.python.org/3.12/whatsnew/3.12.html#id3).

For example, `assertTrue(a == b)` is replaced with `assertEqual(a, b)`.
This produces better error messages, e.g. `error: unexpectedly found 1
and 2 to be different` instead of `error: False`.

This is an ongoing series of commits that are reformatting our Python
code. Reformatting is done with `black` (23.1.0).

If you end up having problems merging this commit because you have made
changes to a python file, the best way to handle that is to run `git
checkout --ours <yourfile>` and then reformat it with black.

RFC: https://discourse.llvm.org/t/rfc-document-and-standardize-python-code-style

Differential revision: https://reviews.llvm.org/D151460

Not needed now that we require python 3.

Reviewed By: kastiglione, JDevlieghere

Differential Revision: https://reviews.llvm.org/D131761

With lldb (& llvm) requiring Python 3.6+, use of the `six` module can be removed.

Differential Revision: https://reviews.llvm.org/D131304

Eliminate boilerplate of having each test manually assign to `mydir` by calling
`compute_mydir` in lldbtest.py.

Differential Revision: https://reviews.llvm.org/D128077

Follow to D127355, converting more `assertEquals` to `assertState`.

Differential Revision: https://reviews.llvm.org/D127378