[llvm] [LangRef] Clarify definition of fragments and debug intrinsics (PR #82019)

[Scott Linder via llvm-commits]

================
@@ -130,6 +130,40 @@ debugging information influences optimization passes then it will be reported
 as a failure.  See :doc:`TestingGuide` for more information on LLVM test
 infrastructure and how to run various tests.
 
+.. _variables_and_variable_fragments:
+
+Variables and Variable Fragments
+================================
+
+Source language variables (or just "variables") are represented by `local
----------------
slinder1 wrote:

I think the terminology gets a bit fuzzy, because "constants" can mean different things in different source languages anyway, right?

I didn't audit every other mention of "variable" in the document, but I imagine this same ambiguity comes up elsewhere, so it would be ideal to get a consistent definition to point back at. DWARF seems to call these "data objects" and says:

```
Chapter 4
Data Object and Object List Entries
This section presents the debugging information entries that describe individual
data objects: variables, parameters and constants, and lists of those objects that
may be grouped in a single declaration, such as a common block.
```

Maybe we can just adopt "data object" here?

https://github.com/llvm/llvm-project/pull/82019