Fixes https://github.com/llvm/llvm-project/issues/140149

These date back to when the non-intrinsic format of variable locations
was still being tested and was behind a compile-time flag, so not all
builds / bots would correctly run them. The solution at the time, to get
at least some test coverage, was to have tests opt-in to non-intrinsic
debug-info if it was built into LLVM.

Nowadays, non-intrinsic format is the default and has been on for more
than a year, there's no need for this flag to exist.

(I've downgraded the flag from "try" to explicitly requesting
non-intrinsic format in some places, so that we can deal with tests that
are explicitly about non-intrinsic format in their own commit).

This PR aims to remove undefined behavior from tests.

This patch makes the final major change of the RemoveDIs project, changing the
default IR output from debug intrinsics to debug records. This is expected to
break a large number of tests: every single one that tests for uses or
declarations of debug intrinsics and does not explicitly disable writing
records. 

If this patch has broken your downstream tests (or upstream tests on a
configuration I wasn't able to run):
1. If you need to immediately unblock a build, pass
`--write-experimental-debuginfo=false` to LLVM's option processing for all
failing tests (remember to use `-mllvm` for clang/flang to forward arguments to
LLVM).
2. For most test failures, the changes are trivial and mechanical, enough that
they can be done by script; see the migration guide for a guide on how to do
this: https://llvm.org/docs/RemoveDIsDebugInfo.html#test-updates
3. If any tests fail for reasons other than FileCheck check lines that need
updating, such as assertion failures, that is most likely a real bug with this
patch and should be reported as such.

For more information, see the recent PSA:
https://discourse.llvm.org/t/psa-ir-output-changing-from-debug-intrinsics-to-debug-records/79578

When cloning instructions from one basic block to another,
the debug values are not remapped, in the same was as the
normal instructions.

Reverted due to some test failures on some buildbots.

https://lab.llvm.org/buildbot/#/builders/67/builds/14669

This reverts commit aa436493ab7ad4cf323b0189c15c59ac9dc293c7.

Fixes the prior issue in which the symbol for a cl-arg was unavailable to
some binaries.

This reverts commit dc06d75ab27b4dcae2940fc386fadd06f70faffe.

Reverted due to failures on buildbots, where a new cl flag was placed
in the wrong file, resulting in link errors.

https://lab.llvm.org/buildbot/#/builders/198/builds/8548

This reverts commit 0b398256b3f72204ad1f7c625efe4990204e898a.

This patch adds support for printing the proposed non-instruction debug
info ("RemoveDIs") out to textual IR. This patch does not add any
bitcode support, parsing support, or documentation.

Printing of the new format is controlled by a flag added in this patch,
`--write-experimental-debuginfo`, which defaults to false. The new
format will be printed *iff* this flag is true, so whether we use the IR
format is completely independent of whether we use non-instruction debug
info during LLVM passes (which is controlled by the
`--try-experimental-debuginfo-iterators` flag).

Even with the flag disabled, some existing tests need to be updated, as this
patch causes debug intrinsic declarations to be changed in a round trip,
such that they always appear at the end of a module and have no attributes
(this has no functional change on the module).

The design of this new IR format was proposed previously on
Discourse, and any further discussion about the design can still be
contributed there:

https://discourse.llvm.org/t/rfc-debuginfo-proposed-changes-to-the-textual-ir-representation-for-debug-values/73491